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کمک کمک به خدا همه گوگل و سرچ واسه این میل سرور گشتم اما مطلبی که به درده کنفرانسو این که بخوای جلوی بچه ها بدی نیس همش نرم افزارارو توضیح دادهه من خودم نمی دونم میل سرور چی هست به چه دردی می خورهه سرگذشتش چیه خوب جواب بدین دیگه
به خدا توی شونصد جا عضو شدم همه بالای پی اچ دی توضیح دادن می خونم نمی فهمم چی کا کنم ؟؟؟؟؟؟؟؟:(
[RIGHT]قرار نیست اینجا مطلب کنفرانس شما را کسی آماده کند.شما خودتان باید برای بدست آوردن نمره دروس دانشگاهی تلاش کنید ، نه کسان دیگر جای شما. کمکی که به شما میشود کرد این است شما باید بدانید که ایمیل چیست و از چه پروتکل هایی استفاده میکند.
با تشکر و سپاس
به طور مثال تاریخچیه ایمیل
[LEFT][CODE]http://www.livinginternet.com/e/ei.htm[/CODE][/LEFT]
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مرسی لطف کردید واقعا ..........
اما.....
باشه اشکال نداره همین کارا رو می کنید که بچه ها از درس خوندن زده می شن ندین نخواستم ولی نمیدونم چرا بلدین واسه موضو عای دیگه فرت فرت مقاله بدین فقط واسه میل سرور ندارین .؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟
[LEFT][CODE]http://my-addr.com/i/understanding_how_email_works/how_does_an_email_server_work/what_is_email.php[/CODE]
[B]What is email[/B]
[B]Electronic mail[/B], often abbreviated to [B]e-mail[/B], [B]email[/B], is any method of creating, transmitting, or storing primarily text-based human communications with digital communications systems. What is email- e-mail is the exchange of computer-stored messages by [B]telecommunication[/B]. Historically, a variety of electronic mail system designs evolved that were often incompatible or not interoperable.
E-mail was one of the first uses of the Internet and is still the most popular use Email based on the [B]Simple Mail Transfer Protocol (SMTP)[/B], first published as Internet Standard 10 ([B]RFC 821[/B]) in 1982. E-mail can also be exchanged between online service provider users and in networks other than the Internet, both public and private.
[B]Understanding how email works[/B]
Modern [B]e-mail systems[/B] are [B]based on a store-and-forward model[/B] in which e-mail computer server systems, accept, forward, or store messages on behalf of users, who only connect to the e-mail infrastructure with their personal computer or other network-enabled device for the duration of message transmission or retrieval to or from their designated server. See image to understanding how email works. So it working like peer-to-peer, user sending letter to some address, mail delivery system sending this letter to server that responsible for mail box, server store this letter and other user (owner of email box) can read.
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[B]How does an email server work[/B]
Server have connection to internet and some rules and policies. How does an email server work - mail server having some [B]SMTP server[/B] (software) that [B]listening port 25[/B] (port 25 linked with smtp -used for e-mail routing between mail servers). There are list of registerd emails on server, if server recieving message to mail box that is registered here it store it in database and mark it as message to mailbox [email]xxxx@xxx.com[/email]. User (or some Web Tool) with [B]using POP3 or IMAP[/B] connecting to server and asking status of mailbox and as result [B]server giving stored messages[/B].
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[LEFT][CODE]http://www.buzzle.com/articles/how-does-an-email-server-work.html[/CODE][B]How does an Email Server Work[/B]
[CENTER][LEFT] Email or electronic mail is the way the world communicates today. It is the fastest form of text communication, over large distances. Rarely do we wonder about how things that matter to us, work. Have you ever wondered how an email server works? How sending and receiving mail is made possible? Read on to know about how email system works through mail servers
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Could we netizens imagine a life without email? Though email is a novelty for the older generation, the young generation hardly uses any other form of communication. This is because email is probably the fastest way of communication.
Though nothing can be compared with the beauty of a handwritten letter, speed matters and that is what makes email more popular. Email communication has reduced the use and waste of paper. It is easier to maintain correspondence. Businesses world over, are switching over to email communication and thus they have indirectly changed the pace of business processes.
Most of the technologies, like email, are taken for granted. One never thinks about how an email is made possible. How does an email server work? The email system was in use even before the [URL="http://www.buzzle.com/articles/internet-technology/"]Internet[/URL] was made operational. The first mail system was developed for the ARPANET which was a defense related internal network of the US government. The first modern type of mail that resembled today's mail was sent in 1971. Today, millions of emails are sent every second, all over the world! How is the journey of your text message, typed from your personal computer to a distant friend, thousands of kilometers away, made possible? Let us understand how your email makes this journey through routing stations called email servers.
[B]Working of an Email Server[/B]
Everything that happens on the internet is through the client - [URL="http://www.buzzle.com/articles/web-servers/"]server[/URL] communication. A client is any computer connected to the internet through a unique internet protocol address. A server is another computer connected to the internet and does the task of hosting and serving web pages and makes the email system possible. Servers are actually computer programs that run on high speed machines. These machines are designed to handle the requests of millions of clients at a time who access a webpage or email service which they are using on their machine. in simple words this process is known as [URL="http://www.buzzle.com/articles/web-hosting/"]web hosting[/URL].
An email system is made possible by two types of servers. One is the SMTP server and other is the POP3 or IMAP sever. Many of us normally use a mail client software like Microsoft Outlook or the latest Mozilla Thunderbird that downloads the incoming email on your machine, from the mail server of the particular [URL="http://www.buzzle.com/articles/email-accounts/"]email account[/URL] you use, on sites like gmail or yahoo or send mail. Let us understand how it all works in terms of client - server communication.
[B]SMTP Server[/B]
SMTP stands for 'Simple Mail Transfer Protocol'. A protocol is an algorithm or procedure of communication, for a particular purpose. This server program exclusively handles the sending part of a mail. When you login to your mail account through a mail client like, outlook express or access directly through a site like hotmail, your client computer communicates with the SMTP server of your email site. An email id is by default in the format 'username@mailsite.com'.
The SMTP server receives the sent mail through port 25. Different ports of a server machine are assigned for certain specific tasks. Then the SMTP server separates the user name and the site name. If the site name is the same as the mail site from which it is sent, then it forwads the mail to its POP3 or IMAP server, which handles incoming mail. For example, if I am sending the mail from my gmail account and the recipient's address is also a gmail account then the gmail SMTP server will simply forward the mail to the POP3 or IMAP gmail server.
If on the other hand, the sent email id belongs to a different site like yahoomail then the gmail SMTP server will contact the [URL="http://www.buzzle.com/articles/domain-name-server-dns-basics.html"]DNS[/URL] (Domain name server) and ask for the IP addresses of the yahoomail server and forward the mail to the yahoomail SMTP server. A mail is a text file which is then forwarded by the yahoomail SMTP server to its POP3 or IMAP server. This server stores it into a particular file dedicated to the recipient's mail account.
Many a times it happens that the SMTP server cannot locate the IP address of the mail recipient server. In such cases, the sent mail is queued and periodically sent again. In case its not able to send the mail, the SMTP server generates a 'mailer daemon' message which informs the sender of failure in message delivery and the reasons for the failure.
[B]POP3 and IMAP Server[/B]
The POP3 server handles the other end of the emailing job. POP stands for 'Post Office protocol'. Through the server port 110, the POP3 server receives your request for reading mail after you log in.Gmail's POP3 server, maintains a detailed text file for every account that is registered on it. All the mail messages delivered through the SMTP server communication are pasted in that text file, one after the other along with all the required delivery timing and other details. When you want to read the mail, it analyzes the text file and separates each mail by header, subject and sender's name and serves it on your machine. The only disadvantage of a POP3 server is that once you download all your incoming messages through a mail client, they do not remain on the server machine. That is, they are erased from there.
The IMAP (Internet Message Access Protocol) server is an improvement of POP3 server and takes care of the only disadvantage it has. What it does is, it maintains the original copy of your incoming mail text file on the server, even after you download it. So with an IMAP server, you can access your mail from any machine and download the mails on the machine or read them live on the site itself, without downloading.
[B]Email Attachments[/B]
Email attachments are extra files attached to the mail which may or may not be text files. The attachments are sent through a mail by encoding there content into another text format and pasting them in the mail itself. These days, MIME (Multipurpose internet Email Extensions) allow audio and video file attachments.
Thus the working of an email system is quite simple in principle. The mail servers handle millions of such requests from world over, every minute. Its one of the most advanced, automatic postal mailing system of the world. Thanks to email servers, we can stay in touch with our dear ones, no matter in which corner of the world they are!
By [URL="http://www.buzzle.com/authors.asp?author=29994"]Gray Pilgrim[/URL]
Published: 7/16/2009[/LEFT]
[LEFT][CODE]http://www.buzzle.com/articles/how-does-the-email-system-work.html[/CODE]
[B]How does the Email System Work[/B]
Email services are used by millions of people world wide, for the transmission of text, data, etc. Read on to know how does the email system work.
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Email accounts are an indispensable part of our day-to-day lives, both at the organizational and individual level. Most of the formal [URL="http://www.buzzle.com/articles/business-communications/"]business communications[/URL] within a company, are carried out through emails. This medium provides a quick as well as secured transmission of text, files, graphics, etc. E-mail systems are primarily based on a store-and-forward model, which enables the computer server to accept, forward, deliver and store messages. Looking at the speed with which these emails are delivered, one might marvel at how does the email system work and how the whole concept evolved. The history of global Internet e-mail service dates back to 1973, when the standards for encoding of messages were proposed. Emails sent in the early 1970s were very similar to ones which constitute the [URL="http://www.buzzle.com/articles/internet-technology/"]Internet[/URL] traffic today. Initially the network-based email transmission used the [URL="http://www.buzzle.com/articles/file-transfer-protocol-ftp/"]File Transfer Protocol (FTP)[/URL], but today it is governed by the Simple Mail Transfer Protocol (SMTP). Here is a brief description about how does the email system work.
[B]A Typical Email Address[/B]
[email]user@provider.com[/email]
In the address mentioned above, 'user' refers to the recipient's user name. Generally these user names are a single word representation of any convenient choice of name by a user. The naming conventions for different companies vary, however, the basics remain the same. The domain name of the organization is reflected by the 'provider' part of the address and it tells about the location of the user's mailbox. The last part, 'com', refers to the type of organization providing the mail server. There are various organizations like com (commercial), gov (government), mil (military), edu (educational institution), org (non-profit organization), etc.
[B]Working of the Email System[/B]
After composing an email, when a user clicks on the 'send' button, it actually takes a non-specific route, which varies from message to message. The email is first wrapped up in a digital envelop which contains the recipient's address, sender's address, and various other things. The SMTP (Simple Mail Transport Protocol) server is used for the purpose of handling the outgoing mails. An email is basically divided into two parts:
[LIST][*][B]Header[/B]: The header field consists of the summary (subject) of the mail, its sender, receiver and other relevant information.[*][B]Body[/B]: The body field consists of the text and attachments inside the mail and sometimes a signature block at the end. Both these fields (header and body) resemble those of a regular letter.[/LIST]
In case the email has to be sent to an address of the same domain, the SMTP server would simply hand the message to the POP3 server of the same, using the delivery agent. Otherwise it communicates with the [URL="http://www.buzzle.com/articles/domain-name-server-dns-basics.html"]DNS (Domain Name Server)[/URL], in order to find the [URL="http://www.buzzle.com/articles/detect-ip-address-how-to-find-an-ip-address.html"]IP address[/URL] of the destination host. An email takes a number of stops before reaching its destination, and at each stop, it is stored temporarily. These intermediate halts also allow the email to find the optimum path towards its ultimate destination. On reaching the recipient's network, the email is routed to the user's inbox, by the email computer. Once it gets stored in the inbox, the recipient can easily see it by logging into his account and opening the mail.
The whole process of email transmission might seem like a lengthy task, however, as the messages travel at nearly the speed of light, the longest hop between networks takes less than the blinking of an eye. Almost all the real e-mail system consists of, is two different servers, namely the SMTP server, which handles outgoing mails, and the POP3 (Post Office Protocol) server or an IMAP server, for handling the incoming mails. It is always good to know how does the email system work, in order to be aware of the security and [URL="http://www.buzzle.com/articles/email-privacy-issues.html"]privacy[/URL] issues related to it.
By [URL="http://www.buzzle.com/authors.asp?author=26545"]Swapnil Srivastava[/URL]
Published: 7/13/2009
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[LEFT][CODE]http://www.buzzle.com/articles/email-privacy-issues.html[/CODE]
[B]Email Privacy Issues[/B]
Internet, a network of networks is susceptible to being attacked. Emails carrying personal messages or business information are in danger of being hacked. Read on to know about the various email privacy issues and their resolutions.
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The Internet, as we all are well aware of, has become a part of everyday life. Internet is the need for most of the transactions occurring across the globe, it is one of the best means of communication; it is the best way to reach out to the masses and is precisely the technological boon that has made the world a small place to live. Emails are an integral part of the Internet. They serve as communicators between friends world over. To me, emails are options similar to the idea of penfriending of the olden times. Emails travel along the network, take the right paths and reach the intended receiver. They help you stay in touch with close friends in this busy life of today. As, emails are so important for all the computer savvy people, email privacy has become an equally important concern. Email privacy issues emerge when it comes to sending plain text over the Internet. Let us look at the email privacy issues in detail.
[B]Email Privacy Issues[/B]
Mails contain headers and the tracing of mails includes the analysis of email header information. An email header contains the source of the message and the list of every point along which the mail has traveled. The examination of an email header can give the information about the sender as also the sender machine's IP address. Moreover an email traveling through many computers across the network is vulnerable to get accessed by intruders.
Secondly, spam, the most irritable issue, is also an email privacy issue. Spam mails eat up huge amounts of bandwidths and annoy the receivers. Unsolicited messages are often used to compel the users to reveal their personal information. Spam mails are commonly used to ask for information that can be used by the attackers. Trojans can attack a computer system in dangerous ways. They are powerful enough to give the attackers complete access to a user's computer system. Trojans include programs, which log the users' keystrokes, thus hacking personal information and passwords keyed in through that computer system.
The safeguarding of email messages from unauthorized access and inspection is known as electronic privacy. Much of the Internet is susceptible to attacks. Emails travel across the unprotected paths of the Internet, becoming vulnerable to attack by intruders. E-mails are subject to unauthorized access, revealing confidential information on the network, thus breaching email privacy. Emails are susceptible to eavesdropping. They journey across several routers and smaller networks and if unshielded, are bound to be attacked. An insufficiently protected router can serve as means of an unauthorized access to emails. Intelligent software can screen email contents quite easily. Moreover emails receivers tend to compromise email privacy by indiscriminately forwarding the emails. Indiscriminate forwarding is often responsible for revelation of contact information and names of all those in that email thread.
Technology has offered solutions to the email privacy issues. The issues have been resolved to a certain extent by the successful implementation of security measures. The security measures include cryptography, digital signatures and the use of secure protocols, which can ensure email privacy to a certain extent.
PGP (Pretty Good Privacy) is one of the encryption standards that encrypts and decrypts the email message. This standard of encryption is a part of most of today's operating systems. Email encryption is another method that achieves email privacy. It is achieved by means of public key cryptography. The popularly used protocols for email encryption are S/MIME, TLS and OpenPGP.
Digital signatures provide us with another way of ensuring email privacy. A digitally signed email message confirms to the receiver, the identity of the sender, thus enabling email privacy. A digitally signed electronic document serves as an assurance of the unaltered and original nature of the email content. This technique fights email spoofing, which involves a manipulation of an email header to make the email appear to have originated from another source.
Email authentication methods are used to equip messages with verifiable information sufficient for the receiver to recognize the nature of incoming messages. In an effort to stop spamming, the valid identity of an email has to be checked. The Transmission Control Protocol and the IP address registries help recipients of emails to verify the IP addresses of the sender. Blacklisting attempts to segregate IP addresses that are of spammers who intend to breach email privacy. But due to the use of dynamic IP addresses, blacklisting fails to become a foolproof plan to fight email privacy issues.
Technology has raised email privacy issues and human intellect has succeeded in finding remedies to them. But when it is about safeguarding privacy, ethics is something that matters most.
By [URL="http://www.buzzle.com/authors.asp?author=15890"]Manali Oak[/URL]
Published: 8/3/2008
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[LEFT][CODE]http://www.buzzle.com/articles/email-lookup-find-email-address.html[/CODE][B]Email Lookup - Find Email Address[/B]
Technology has found a tremendous growth in the field of communication. Among them, communication through email plays a major role…
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[LEFT]Technology has found a tremendous growth in the field of communication. Nowadays people, though they are separated by distance, maintain a good deal of communication between them through various technologies. Among them, communication through email plays a major role.
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[B]E-Mail[/B]
The electronic-mail allows the users to send messages to another through the World Wide Web. This is achieved with the help of email addresses i.e. a person can contact another only if he has the email address of the person he wishes to contact. But the condition becomes worse when the user
[I]Loses or forgets the email address
When the address has been changed
Wishes to contact a person whose email id is not known.[/I]
To overcome these conditions, a method called email lookup has been adopted by the users to find the email addresses.
[B]What is Email Lookup Service?[/B]
Email lookup service is used to find the address of a person by means of his name, location etc. Various email address directories, search engines, college universities use this method to assist people in finding email addresses. Nowadays several soft wares are also introduced to extract addresses from the internet and hence, helping the people to make their work easier.
Users should be more careful and cautious while using email lookups. Many of the users go for traditional search techniques to find the personal information using public records. This may sometimes result in failure because the public records will not have the information of all the email addresses. Payable email lookup is also available but care should be taken while using it. In-depth search often results in more costs and efforts but without any fruitful outcomes.
[B]Check for This[/B]
Users should go for the email look up which uses the best search engines to find the email addresses. It should also search the email directories which contain most of the public records and also updates itself with the edited email address services if in case there is any. An email lookup consists of first name, last name, city and state as attributes. Users who want to search an email address should fill these columns with the corresponding available details of the intended person. The search engine searches for the address in all its available resources and returns back the email address. If in case it is unable to find, it tries searching the additional databases of public records like criminal records, driving records, current and prior addresses, marriage and divorce records, law suits and other possible aliases.
Many colleges, universities, companies have a separate web page in their website exclusively for email lookup. This web page consists of the columns to be filled in with the details of the student, faculty or the staff member whom the user is searching. After submitting the details, the email address is retrieved by the user. But not all the addresses can be retrieved by this method due to the confidentiality factor. Software like Email Spider Easy and Internet Email address extractor are easier to use and allows more than 800 email extraction threads simultaneously. By setting out the search words and parameters, these tools extract the email addresses from the web pages, text files, scripts etc.
[B]Reverse Email[/B]
Another method called reverse email lookup is available to find the details of a person with the help of email addresses. This is mostly done by industry professionals to find clues in cyber crimes. With the help of reverse email look up, one can find the user’s name, Internet Service Provider (ISP), geographic location, internet browser, operating system, abuse report contact etc. and therefore retrieve his whereabouts.
Thus email lookup remains as a boon to the users in assisting them to have a constant communication with their fellow beings in spite of the presence of many hindrances.
By [URL="http://www.buzzle.com/authors.asp?author=8136"]Jayashree Pakhare[/URL]
Published: 1/8/2008
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[LEFT][CODE]http://www.buzzle.com/articles/trends-in-free-email-services.html[/CODE]
[B]Trends in Free Email Services[/B]
The current trends in free email services seem inclined towards encouraging people to stay with their existing email accounts for life.
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These days, if you want to get in touch with someone, chances are higher that you'll contact them by email rather than by regular post. Email has become one of those essential things in life that one just can't do without. To be able to send or receive an email you obviously need a valid email address and there are plenty of email providers around the Internet to provide you with this. Temporary and permanent, free and paid-for email services are all available, and which you choose depends on your personal preferences and requirements. If, for example, you need POP3 access, extra-large space and an email address with your own domain name, you will need to go for paid email service. Otherwise a free email service will do just fine. Let's take a look at the trends in free email services.
[B]Trends in Free Email Services:[/B]
Free email services have come a long way from the limited features and limited storage space that were available previously. The major turning point came when Google announced their Gmail service, which was rather remarkable then for offering a 1 GB mailbox. You also got the Google search facility and Google Talk in the same service, as well as some sturdy SPAM protection. Google has since upped its ante to 5.11 GB and, who knows, may up that as well.
Soon after Yahoo and Rediff, the two other major players, announced they were going to be generous to subscribers too, denied that this generosity owed anything to Google's move, and respectively went from a 4 MB mailbox to a 100 MB mailbox and a 5 MB mailbox to a 1 GB mailbox. Yahoo and Rediff are both now offering Unlimited Email Storage. If you have a UK or Canada account, Yahoo also gives you either free POP3 access.
Microsoft didn't want to be left behind. So Hotmail went from a 2 MB mailbox to a 250 MB mailbox. Microsoft has now transitioned to Windows Live Hotmail which started out with 2 GB of online storage and now boasts 5 GB.
Currently the trends in free email services point towards not just towards increasingly larger mail boxes, with greater or unlimited storage spaces, but also stronger SPAM protection, anti-virus check and easy access from anywhere at anytime. In addition, it is almost de rigeur to offer handy features like a notepad, calendar, improved address book, contact importing from Outlook, folders to help you sort your emails by category, ability to send larger files as attachments, a search facility that lets you search by keyword or email, HTML mail capability, right-click support for deleting and forwarding, personal signature for outgoing mail, automatic notification of new email at another address, drag and drop support, and much more. The emphasis seems towards encouraging people to stay with their current email accounts for life.
[B]Free Email Service Providers:[/B]
Some popular and free email service providers are -
[B]Yahoo[/B] – Yahoo has a great and easy-to-use interface and an excellent SPAM protection. You can send and store pictures, text and documents. You can also send 10 MB files as email attachments. If you want more space, the ability to send 20 MB files as email attachments, and no ads, you can buy Yahoo! Mail Plus which comes for $19.95 per year.
[B]Gmail[/B] – Gmail has extensively used AJAX technology which helps it to load quickly. You can store files with third party applications and resources in Gmail.
[B]Windows Live Hotmail[/B] – This too uses AJAX technology. Aside from the 5 GB storage, it comes with some better security measures, so, hopefully, it won't wind up being the Hotbed of Spammers. Windows Live Hotmail has the usual features like Contacts, Calendar and Windows Live Messenger. You can write emails in 35 different languages, so long you know how to.
[B]MyTrashMail[/B] – If you want a temporary email address that is disposable, anonymous and doesn't require any registration or password, this is a good place. They've now gone to a new domain name @trashymail.com because, according to their site 'Receiving over 10,000,000 emails per day is just way to much for a single dedicated server.'
[B]HushMail[/B] – Go for this if you're in the hush-hush business and need to encrypt every email you send. Attachments are also encrypted, so the secret data can be exchanged in due safety.
[B]MuchoMail[/B] – That's 'Mucho', not 'Macho'. Just to be clear. You get 25 MB of storage – 1000 MB if you go paid Premium - and can send up to 3 unlimited-size attachments.
By [URL="http://www.buzzle.com/authors.asp?author=762"]Sonal Panse[/URL]
Published: 11/27/2007
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[LEFT][CODE]http://communication.howstuffworks.com/email.htm/printable[/CODE][B]How E-mail Works[/B]
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by [URL="http://communication.howstuffworks.com/email.htm/about-author.htm#brain"]Marshall Brain[/URL] and [URL="http://communication.howstuffworks.com/email.htm/hsw-contact.htm"]Tim Crosby[/URL]
Browse the article [B][URL="http://communication.howstuffworks.com/email.htm"] How E-mail Works[/URL][/B]
Introduction to How E-mail Works
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[SIZE=2][B]E-mail is used every day[/B][/SIZE][SIZE=2][B]by millions of [/B][/SIZE][B][SIZE=2]people all [/SIZE][/B][B][SIZE=2]over the world.[/SIZE][/B] Every day, the citizens of the Internet send each other billions of e-mail messages. If you're online a lot, you yourself may send a dozen or more e-mails each day without even thinking about it. Obviously, e-mail has become an extremely popular communication tool.
Have you ever wondered how e-mail gets from your computer to a friend halfway around the world? What is a POP3 server, and how does it hold your mail? The answers may surprise you, because it turns out that e-mail is an incredibly simple system at its core. In this article, we'll take an in-depth look at e-mail and how it works.
[B]An E-mail Message[/B]
According to [URL="http://communication.howstuffworks.com/email.htm/framed.htm?parent=email.htm&url=http://www.darwinmag.com/read/010102/buzz_mover.html"]Darwin Magazine: Prime Movers[/URL], the first e-mail message was sent in 1971 by an engineer named Ray Tomlinson. Prior to this, you could only send messages to users on a single machine. Tomlinson's breakthrough was the ability to send messages to other machines on the Internet, using the @ sign to designate the receiving machine.
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[SIZE=1]James Nielsen/AFP/[URL="http://howstuffworks.com/framed.htm?parent=email.htm&url=http://www.gettyimages.com/"]Getty Images[/URL][/SIZE]
[SIZE=2][B]David Ryckaert (right) and his wife Nathalie from Brussels, Belgium, check their e-mail during Hurricane Katrina in New Orleans, La., in 2005.[/B]
[/SIZE] An e-mail message has always been nothing more than a simple [B]text message[/B] -- a piece of text sent to a recipient. In the beginning and even today, e-mail messages tend to be short pieces of text, although the ability to add attachments now makes many messages quite long. Even with attachments, however, e-mail messages continue to be [URL="http://howstuffworks.com/framed.htm?parent=email.htm&url=http://communication.howstuffworks.com/sms.htm"]text messages[/URL] -- we'll see why when we get to the section on attachments. [B]E-mail Clients[/B]
You've probably already received several e-mail messages today. To look at them, you use some sort of [B]e-mail client[/B]. Many people use well-known, stand-alone clients like Microsoft Outlook, Outlook Express, Eudora or Pegasus. People who subscribe to free e-mail services like Hotmail or Yahoo use an e-mail client that appears in a [URL="http://howstuffworks.com/framed.htm?parent=email.htm&url=http://computer.howstuffworks.com/web-page.htm"]Web page[/URL]. If you're an AOL customer, you use AOL's e-mail reader. No matter which type of client you're using, it generally does four things:
[LIST][*]Shows you a list of all of the messages in your mailbox by displaying the [B]message headers[/B]. The header shows you who sent the mail, the subject of the mail and may also show the time and date of the message and the message size.[*]Lets you select a message header and read the body of the e-mail message.[*]Let's you create new messages and send them. You type in the e-mail address of the recipient and the subject for the message, and then type the body of the message.[*]Lets you add attachments to messages you send and save the attachments from messages you receive.[/LIST]
Sophisticated e-mail clients may have all sorts of bells and whistles, but at the core, this is all that an e-mail client does.
A Simple E-mail Server
Given that you have an e-mail client on your machine, you are ready to send and receive e-mail. All that you need is an [B]e-mail server[/B] for the client to connect to. Let's imagine what the simplest possible e-mail server would look like in order to get a basic understanding of the process. Then we will look at the real thing.
[IMG]http://static.howstuffworks.com/gif/webserver-basic-sm.gif[/IMG]
If you've read [URL="http://howstuffworks.com/framed.htm?parent=email.htm&url=http://computer.howstuffworks.com/web-server.htm"]How Web Servers Work[/URL], then you know that machines on the Internet can run software applications that act as [B]servers[/B]. There are Web servers, FTP servers, telnet servers and e-mail servers running on millions of machines on the Internet right now. These applications run all the time on the server machine and they listen to specific [B]ports[/B], waiting for people or programs to attach to the port. The simplest possible e-mail server would work something like this:
[LIST=1][*]It would have a list of e-mail accounts, with one account for each person who can receive e-mail on the server. My account name might be [B]mbrain[/B], John Smith's might be [B]jsmith[/B], and so on.[*]It would have a text file for each account in the list. So, the server would have a text file in its directory named MBRAIN.TXT, another named JSMITH.TXT, and so on.[*]If someone wanted to send me a message, the person would compose a text message ("Marshall, Can we have lunch Monday? John") in an e-mail client, and indicate that the message should go to mbrain. When the person presses the Send button, the e-mail client would connect to the e-mail server and pass to the server the name of the recipient (mbrain), the name of the sender (jsmith) and the body of the message.[*]The server would format those pieces of information and append them to the bottom of the MBRAIN.TXT file. The entry in the file might look like this:[/LIST]
[INDENT] [INDENT] From: jsmith
To: mbrain
Marshall,
Can we have lunch Monday?
John[/INDENT][/INDENT]There are several other pieces of information that the server might save into the file, like the time and date of receipt and a subject line; but overall, you can see that this is an extremely simple process.
We'll look at the SMTP server in the next section.
More Complex Servers
As other people sent mail to mbrain, the server would simply append those messages to the bottom of the file in the order that they arrived. The text file would accumulate a series of five or 10 messages, and eventually I would log in to read them. When I wanted to look at my e-mail, my e-mail client would connect to the server machine. In the simplest possible system, it would:
[LIST=1][*]Ask the server to send a copy of the MBRAIN.TXT file[*]Ask the server to erase and reset the MBRAIN.TXT file[*]Save the MBRAIN.TXT file on my local machine[*]Parse the file into the separate messages (using the word "From:" as the separator)[*]Show me all of the message headers in a list[/LIST]
When I double-clicked on a message header, it would find that message in the text file and show me its body.
As you can see, this is a very simple system. Surprisingly, the real e-mail system that you use every day isn't much more complicated than this.
[B]The Real E-mail System[/B]
For the vast majority of people right now, the real e-mail system consists of two different servers running on a server machine. One is called the [B]SMTP server[/B], where SMTP stands for Simple Mail Transfer Protocol. The SMTP server handles outgoing mail. The other is either a [B]POP3 server[/B] or an [B]IMAP server[/B], both of which handle incoming mail. POP stands for Post Office Protocol, and IMAP stands for Internet Mail Access Protocol. A typical e-mail server looks like this:
[IMG]http://static.howstuffworks.com/gif/email2.gif[/IMG]
The SMTP server listens on well-known port number 25, POP3 listens on port 110 and IMAP uses port 143 (see [URL="http://computer.howstuffworks.com/web-server.htm"]How Web Servers Work[/URL] for details on ports).
The SMTP Server
Whenever you send a piece of e-mail, your e-mail client interacts with the SMTP server to handle the sending. The SMTP server on your host may have conversations with other SMTP servers to deliver the e-mail.
[IMG]http://static.howstuffworks.com/gif/email1.gif[/IMG] Let's assume that I want to send a piece of e-mail. My e-mail ID is brain, and I have my account on howstuffworks.com. I want to send e-mail to [email]jsmith@mindspring.com[/email]. I am using a stand-alone e-mail client like Outlook Express.
When I set up my account at howstuffworks, I told Outlook Express the name of the mail server -- mail.howstuffworks.com. When I compose a message and press the Send button, here's what happens:
[LIST=1][*]Outlook Express connects to the SMTP server at mail.howstuffworks.com using port 25.[*]Outlook Express has a conversation with the SMTP server, telling the SMTP server the address of the sender and the address of the recipient, as well as the body of the message.[*]The SMTP server takes the "to" address (jsmith@mindspring.com) and breaks it into two parts: the recipient name (jsmith) and the domain name (mindspring.com). If the "to" address had been another user at howstuffworks.com, the SMTP server would simply hand the message to the POP3 server for howstuffworks.com (using a little program called the [B]delivery agent[/B]). Since the recipient is at another domain, SMTP needs to communicate with that domain.[*]The SMTP server has a conversation with a [B]Domain Name Server[/B], or [B]DNS[/B] (see [URL="http://computer.howstuffworks.com/web-server.htm"]How Web Servers Work[/URL] for details). It says, "Can you give me the IP address of the SMTP server for mindspring.com?" The DNS replies with the one or more IP addresses for the SMTP server(s) that Mindspring operates.[*]The SMTP server at howstuffworks.com connects with the SMTP server at Mindspring using port 25. It has the same simple text conversation that my e-mail client had with the SMTP server for HowStuffWorks, and gives the message to the Mindspring server. The Mindspring server recognizes that the domain name for jsmith is at Mindspring, so it hands the message to Mindspring's POP3 server, which puts the message in jsmith's mailbox.[/LIST]
If, for some reason, the SMTP server at HowStuffWorks cannot connect with the SMTP server at Mindspring, then the message goes into a queue. The SMTP server on most machines uses a program called [B]sendmail[/B] to do the actual sending, so this queue is called the [B]sendmail queue[/B]. Sendmail will periodically try to resend the messages in its queue. For example, it might retry every 15 minutes. After four hours, it will usually send you a piece of mail that tells you there is some sort of problem. After five days, most sendmail configurations give up and return the mail to you undelivered.
The SMTP server understands very simple text commands like HELO, MAIL, RCPT and DATA. The most common commands are:
[LIST][*][B]HELO[/B] - introduce yourself[*][B]EHLO[/B] - introduce yourself and request extended mode[*][B]MAIL FROM:[/B] - specify the sender[*][B]RCPT TO:[/B] - specify the recipient[*][B]DATA[/B] - specify the body of the message (To, From and Subject should be the first three lines.)[*][B]RSET[/B] - reset[*][B]QUIT[/B] - quit the session[*][B]HELP[/B] - get help on commands[*][B]VRFY[/B] - verify an address[*][B]EXPN[/B] - expand an address[*][B]VERB[/B] - verbose[/LIST]
The POP3 and IMAP Servers
In the simplest implementations of POP3, the server really does maintain a collection of text files -- one for each e-mail account. When a message arrives, the POP3 server simply appends it to the bottom of the recipient's file.
When you check your e-mail, your e-mail client connects to the POP3 server using [B]port 110[/B]. The POP3 server requires an account name and a password. Once you've logged in, the POP3 server opens your text file and allows you to access it. Like the SMTP server, the POP3 server understands a very simple set of text commands. Here are the most common commands:
[LIST][*][B]USER[/B] - enter your user ID[*][B]PASS[/B] - enter your password[*][B]QUIT[/B] - quit the POP3 server[*][B]LIST[/B] - list the messages and their size[*][B]RETR[/B] - retrieve a message, pass it a message number[*][B]DELE[/B] - delete a message, pass it a message number[*][B]TOP[/B] - show the top x lines of a message, pass it a message number and the number of lines[/LIST]
Your e-mail client connects to the POP3 server and issues a series of commands to bring copies of your e-mail messages to your [URL="http://computer.howstuffworks.com/pc.htm"]local machine[/URL]. Generally, it will then delete the messages from the server (unless you've told the e-mail client not to).
You can see that the POP3 server simply acts as an interface between the e-mail client and the text file containing your messages. And again, you can see that the POP3 server is extremely simple. You can connect to it through telnet at port 110 and issue the commands yourself if you would like to (see [URL="http://computer.howstuffworks.com/web-server.htm"]How Web Servers Work[/URL] for details on telnetting to servers).
[IMG]http://static.howstuffworks.com/gif/email-soldier.jpg[/IMG]
[SIZE=1]George Frey/[URL="http://howstuffworks.com/framed.htm?parent=email.htm&url=http://www.gettyimages.com/"]Getty Images[/URL][/SIZE]
[SIZE=2][B]Tammy Pruett and her husband Leon read an e-mail from their sons serving in Iraq.[/B]
[/SIZE] [B]The IMAP Server[/B]
As you can see, the POP3 protocol is very simple. It allows you to have a collection of messages stored in a text file on the server. Your e-mail client (e.g. Outlook Express) can connect to your POP3 e-mail server and download the messages from the POP3 text file onto your PC. That is about all that you can do with POP3. Many users want to do far more than that with their e-mail, and they want their e-mail to remain on the server. The main reason for keeping your e-mail on the server is to allow users to connect from a variety of machines. With POP3, once you download your e-mail it's stuck on the machine to which you downloaded it. If you want to read your e-mail both on your desktop machine and your laptop (depending on whether you're working in the office or on the road), POP3 makes life difficult.
IMAP (Internet Mail Access Protocol) is a more advanced protocol that solves these problems. With IMAP, your mail stays on the e-mail server. You can organize your mail into folders, and all the folders live on the server as well. When you search your e-mail, the search occurs on the server machine, rather than on your machine. This approach makes it extremely easy for you to access your e-mail from any machine, and regardless of which machine you use, you have access to all of your mail in all of your folders.
We'll look at IMAP problems and attachments in the next section.
IMAP Problems and Attachments
Your e-mail client connects to the IMAP server using [B]port 143[/B]. The e-mail client then issues a set of text commands that allow it to do things like list all the folders on the server, list all the message headers in a folder, get a specific e-mail message from the server, delete messages on the server or search through all of the e-mails on the server.
One problem that can arise with IMAP involves this simple question: "If all of my e-mail is stored on the server, then how can I read my mail if I'm not connected to the Internet?" To solve this problem, most e-mail clients have some way to cache e-mail on their local machine. For example, the client will download all the messages and store their complete contents on the local machine (just like it would if it were talking to a POP3 server). The messages still exist on the IMAP server, but you now have copies on your machine. This allows you to read and reply to e-mail even if you have no connection to the Internet. The next time you establish a connection, you download all the new messages you received while disconnected and send all the mail that you wrote while disconnected.
[B]Attachments[/B]
Your e-mail client allows you to add attachments to e-mail messages you send, and also lets you save attachments from messages that you receive. Attachments might include word processing documents, spreadsheets, sound files, snapshots and pieces of software. Usually, an attachment is not text (if it were, you would simply include it in the body of the message). Since e-mail messages can contain only text information, and attachments aren't text, there's a problem that needs to be solved.
[IMG]http://static.howstuffworks.com/gif/email-video-mail.jpg[/IMG]
[SIZE=1][URL="http://howstuffworks.com/framed.htm?parent=email.htm&url=http://www.gettyimages.com/Home.aspx"]Getty Images[/URL][/SIZE]
[SIZE=2][B]As e-mail becomes more complex, [/B][/SIZE][SIZE=2][B]attachments do, too, giving us options like video mail. [/B]
[/SIZE] In the early days of e-mail, you solved this problem by hand, using a program called [B]uuencode[/B]. The uuencode program assumes that the file contains binary information. It extracts 3 bytes from the binary file and converts them to four text characters (that is, it takes 6 bits at a time, adds 32 to the value of the 6 bits and creates a text character -- see [URL="http://computer.howstuffworks.com/bytes.htm"]How Bits and Bytes Work[/URL] to learn more about ASCII characters). What uuencode produces, therefore, is an [B]encoded[/B] version of the original binary file that contains only text characters. In the early days of e-mail, you would run uuencode yourself and paste the uuencoded file into your e-mail message. Considering its tremendous impact on society, having forever changed the way we communicate, today's e-mail system is one of the simplest things ever devised! There are parts of the system, like the routing rules in sendmail, that get complicated, but the basic system is incredibly straightforward. The next time you send an e-mail, you'll know exactly how it's getting to its destination.
Check out the next page for simple etiquette rules about writing and sending e-mail messages.
Free and Paid E-mail Services
Whether it's for work or keeping in touch with family and friends, people rely on the Internet to send and receive e-mail messages. According to a March 2007 study by the Pew Internet and American Life Project, 91 percent of U.S. Internet users have gone online to send or read e-mail. The same source reports that 56 percent of e-mail users send or read e-mail as part of a typical day [source: [URL="http://howstuffworks.com/framed.htm?parent=email.htm&url=http://www.email-marketing-reports.com/metrics/email-statistics.htm"]Email Marketing Reports[/URL]].
[IMG]http://static.howstuffworks.com/gif/email-20-copy.jpg[/IMG]
[SIZE=1]Image courtesy of [URL="http://howstuffworks.com/framed.htm?parent=email.htm&url=http://www.google.com"]Google[/URL][/SIZE]
[SIZE=2][B]Services such as Google and Yahoo! provide free e-mail accounts for subscribers.[/B][/SIZE]
An October 2007 study by the market research firm, [URL="http://howstuffworks.com/framed.htm?parent=email.htm&url=http://www.radicati.com/"]The Radicati Group[/URL], reported that 183 billion e-mails were sent daily in 2006. With numbers like that, it's no surprise that there's a large variety of e-mail service providers to choose from. Choices include providers like Gmail or Yahoo! who provide free e-mail service or providers who charge a fee like America Online, Apple or NetZero.
Gmail and Yahoo! make money from advertisers who pay them to expose e-mail account holders to their messages. It's also easy to find reviews of various free e-mail services. Here are few descriptions of free e-mail services:
[LIST][*]Gmail -- Gmail is Google's free e-mail service. It offers online storage that's practically unlimited. It also provides sorting methods that allows users to quickly organize and sift their inbox efficiently for important messages. As a free service, Gmail exposes users to contextual advertisements, which are based on keywords found in the user's e-mail messages. It's versatile in handling many different attachment types and scans for spam, worms and virus.[*]Yahoo! mail -- Perhaps one of the most popular free services, Yahoo! offers unlimited online storage as well as text messaging and RSS news feeds. Using more than a dozen filters, Yahoo! files incoming e-mails and automatically sends junk e-mails to a spam folder and allows you to add e-mails to that folder. It features easy-to-use drag and drop organization tools.[*]MSN Windows Hotmail -- Another well-used free service, Hotmail is supported by Microsoft technology and features 5 GB of online storage space. A versatile desktop design allows users to customize the color and layout of their mail manager. It also offers users the choice of working a classic, familiar format and switching to an updated look with added features when they choose. Microsoft security features coupled with familiar drag-and-drop organization tools add further comfort-of-use for many e-mail users.[/LIST]
E-mail providers who charge a fee may offer additional services such as increased storage space. Sample providers include Juno, EarthLink and Webmail.us.
For example, it's easier to get personalized e-mail addresses -- perhaps incorporating your actual name, for instance - using a paid service. Paid e-mail services often allow users to keep their same e-mail address even if they change their ISP and screen users from advertisers. They often are easier to reach on support issues and special features such as custom spam filters, additional e-mail accounts and mobile access.
Most ISP Internet providers can also serve as an e-mail provider for no additional charge. Other paid e-mail services specialize in small business accounts and can assist businesses in purchasing and maintaining a domain name.
On the next page, we'll offer some etiquette tips for when you write and send e-mail messages.
E-Mail Etiquette
Most people wouldn't think of being rude or obnoxious when they speak to colleagues, clients or their supervisor. But those rules can fall by the wayside when we use e-mail.
The opportunities for rudeness when using e-mail are plentiful and not always easy to recognize. Most people wouldn't use foul language or derogatory terms in business communication. But what about raising one's voice? Is that possible when using e-mail?
[IMG]http://static.howstuffworks.com/gif/e-mail-etiquette.jpg[/IMG]
[SIZE=1]Photographer: Marc Dietrich | Agency: [URL="http://howstuffworks.com/framed.htm?parent=email-etiquette.htm&url=http://www.dreamstime.com"]Dreamstime[/URL][/SIZE]
[SIZE=2][B]Remain professional and polite in your e-mails. [/B][/SIZE][SIZE=2][B]You never know where they'll end up.[/B][/SIZE] Here, we'll discuss some business writing rules and tips for practicing e-mail etiquette.
People are busy, so:
[LIST][*][B]Use the subject line[/B]. You might be tempted to bypass this part of the e-mail, but just remember: everyone is in a hurry, including the recipient of your e-mail. That person will appreciate the clue the subject line provides as to the message content. It helps them prioritize and organize.[*][B]Be brief and concise[/B]. No matter how clever and entertaining a writer you might be, your message recipients will appreciate brevity and clarity. Save the puns and witty turns of phrase for after birthday cards and toasts. State the message quickly followed by clear requests or instructions for any action needed by the recipient.[*][B]Keep it personal[/B]. Routinely copying others on e-mails clogs mailboxes and can lead to the main recipient wondering why you're doing so. Unless you have a specific reason for copying someone, keep the conversation between sender and recipient.[*][B]Reply quickly.[/B] Don't let e-mails sit around in your queue unanswered. Get back to the sender, even if it's to say you need more time to respond.[/LIST]
People are sensitive, so:
[LIST][*][B]Don't over-punctuate.[/B] Adding multiple punctuation marks, such as ???? or !!!! after a sentence makes it seem as though you are shouting or frustrated with the recipient. Use normal punctuation rules.[*][B]Don't use all capitals.[/B] Using all caps MAKES IT SEEM LIKE YOU'RE SHOUTING. Shouting is rude. Use normal capitalization rules. If you need to emphasize something, write "I'd like to emphasize…"[*][B]Read it, out loud, before you send it.[/B] While you may think you're writing exactly what you mean, it pays to read some e-mails out loud to yourself, putting yourself in the recipient's shoes, before hitting that "send" button. Once it's in writing, it's hard to take back. Also, never forget that the recipient has both a printer and "forward" button. Never write something you wouldn't want to have circulated throughout the company or even beyond.[*][B]Don't write when you're angry.[/B] Perhaps one of the most common etiquette rules to break is firing off an e-mail to someone when you're angry, either at them or a situation. See "Read it out loud" above. You can't take it back once you "flame" someone, and it can come back to haunt you.[/LIST]
Not everyone is as hip as you are, so:
[LIST][*][B]Keep the symbols to a minimum.[/B] Using "smiles" is a trendy way to communicate mood and meaning. But do you know the difference between a sarcastic smile and a mischievous one? And even if you're sure you do, can you be sure your recipient does? It's easy to see the potential to unintentionally offend someone using these symbols. Avoid using them.[*][B]Minimize abbreviated phrases.[/B] Using abbreviations such as IMHO (in my humble opinion). FWIW (for what it's worth) and ROTFL (rolling on the floor laughing) can frustrate and confuse the recipient.[/LIST]
E-mail is like as a business letter. Ignoring basic rules can show disrespect for the recipient. Don't let informality spoil the recipient's opinion of you.
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[B]Technology Explained: How Does An Email Server Work?[/B]
As an invention, email probably ranks close to the development of alphabets. We may IM and tweet to our heart’s content but it would be wrong to say that these shortcuts have been sired by the humble email to a certain extent. It has revolutionized communications though it may also have sounded the death knell for the art of letter writing. But that’s technology.
Email is serious but it’s several simple technologies at work, something we take for granted when we click [I]compose[/I] and [I]send[/I]. Behind each email is a powerful engine called the email server which pushes the emails through the internet. Many people use them, but how does an email server work?
To drive a car we need not have the ability to tell a carburetor from a tailpipe, but when it breaks down, that little knowledge helps. Email is less likely to [URL="http://www.makeuseof.com/tag/diagnose-email-server-problems-with-free-tools/"]crash[/URL] but it definitely helps to have a broad picture of how Jim’s mail reaches Jane half across the globe in a blink of an eye.
[B][B]The Big Picture – How does an email go from Sender to Recipient?[/B][/B]
Each email message is nothing but a text file plus the attachments. Just like all data through the internet, an email is also broken into smaller packets. When the sender clicks the [I]send[/I] button, all the packets are uploaded to a central computer (theemail server) that hosts the email service.
The email service then relays these packets through the internet to the server which holds the email service of the recipient. The mail server of the recipient looks for his email address, locates it and places the email within the inbox. The email client reassembles the packets into a complete mail. The recipient logs into his account and downloads the email.
[B][B]Step by Step – How the Little Parts Come Together[/B][/B]
We use an online email service like [URL="http://www.makeuseof.com/tag/how-to-stay-connected-with-gmail/"]Gmail[/URL], [URL="http://www.makeuseof.com/tag/send-and-recieve-yahoo-mail-using-your-desktop-email-client/"]Yahoo Mail[/URL] or AOL to compose an email, add attachments and other data files. Also, we use email client software like [URL="http://www.makeuseof.com/tags/thunderbird"]Thunderbird[/URL], [URL="http://www.makeuseof.com/tags/outlook"]Outlook Express[/URL], Outlook or [URL="http://www.makeuseof.com/tags/mac"]Mac[/URL] OS X’s Mail.
[LIST][*]When we send an email, our computer connects to our email service’s mail server. A [I]server[/I] is a centralized computer which manages a specific type of service. An email server for instance, handles emails. The email server responsible for sending emails is called the [B]SMTP [/B](Simple Mail Transfer Protocol) server. One SMTP server can pass on the mail to another SMTP server and relay it to the destination through several hops.[*]Every email has the sender’s address (e.g. [I]sender@sendermail.com[/I]) and the recipient’s in the [I]To[/I] field (e.g. [I]recipient@recipientmail.com[/I]). When an email is sent, the email client connects to the SMTP server of the sender’s email service (e.g. [I]mailserver.sendermail.com[/I]). The client transmits the address of the sender, the address of the recipient and the content of the message. [CENTER][IMG]http://www.makeuseof.com/wp-content/uploads/2009/08/Diagrammatic-Rep.png[/IMG][/CENTER][*]The SMTP server goes to work at locating the whereabouts of the recipient. Using the recipient’s mail ID (i.e. [email]recipient@recipientmail.com[/email]) it locates the domain name – e.g.[I]recipientmail.com[/I].[*]Note: If the recipient’s mail ID had the same domain name as the sender, then the process would be simpler. The SMTP server would have transferred the mail to its local outgoing mail server (POP3 or IMAP).[*]Each domain name represents a unique Web address, called an [B]Internet protocol (IP) [/B]address. Think of it as postal addresses of the internet. The link between domain names to their IP addresses is stored in the [B]Domain Name Registry[/B]. The SMTP server then contacts the server where the registry is kept ([B]The DNS Server[/B]). The DNS server sends back the address to the SMTP server.[*]The SMTP server then proceeds to hand over the email to the SMTP server of the recipient’s email service (let’s call it mailserver.recipientmail.com). This SMTP server checks and confirms that the mail addressed to [email]recipient@recipientmail.com[/email] belongs to it and hands it over to its counterpart – the [I]POP3 server[/I] (or the [I]IMAP server[/I]).[*][B]Post Office Protocol (POP3)[/B] servers are the servers that do the job of receiving mails. The number [I]‘3’[/I] is the version number of the protocol in use. POP3 servers have mail accounts (our email IDs). Each mail account is mapped to a username-password combination. Once the message is handed over to the POP3 server, it is kept and stored in the mail account till the recipient logs in and checks the mail.[*]An email client connects to the POP3 server and tells it to allow download of the email. Once downloaded to the local machine, POP3 mailboxes do not retain a copy of the email. Thus, you cannot check your emails from another PC as it has already been downloaded. To nail this difficulty, IMAP was introduced. [B]IMAP4 [/B](Internet Message Access Protocol version 4) simply retains a copy of the emails on the server. This allows you to access your e-mail from any location with an internet connection.[/LIST]
[B][B]Simple notes of difference between POP3 and IMAP4[/B][/B]
[CENTER][IMG]http://www.makeuseof.com/wp-content/uploads/2009/08/IMPAP-Settings.png[/IMG][/CENTER]
The obvious differences between the two protocols can be felt. POP3 mails are not limited by mail sizes as they get stored locally on your computer. Also because of less server storage space they are cheaper to support. But they make it difficult to export your emails if you decide to switch email programs or even operating systems.
With IMAP you can just download them again. With IMAP, sent mail and drafts are also uploaded to the server. The one apparent disadvantage of IMAP is its slower speeds because of server based functions.
POP3 is common but IMAP4 is newer and more advantageous for some of these reasons.
I hope next time you sit down to email; you just might appreciate the synergy of technology that makes it all possible. Right now, let me get back to my inbox and check what it has in store for me.
By the way, did you know that email came much, much before the internet? Probably, as early as [URL="http://www.nethistory.info/History%20of%20the%20Internet/email.html"]1965[/URL]!
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[RIGHT]واقعاً متأسفم که اينگونه مينويسيد ، متأسفم که يک دانشجو نميتواند در گوگل جستجو کند، وقتی به شما گفته شد که برويد و پرتوکلها را ياد بگيريد برای همين است
شما هنوز نميدانيد چيزی که ميخواهيد به انگليسی چه گفته ميشود که به دنبال آن باشيد و وقتی مينويسم زبان انگليسی خود را تقويت کنيد، ياد بگيريد در اينترنت جستجو کنيد . ميگويند مغرور هستم
[/RIGHT]
