Tuesday, 9 December 2014

Mail Server Protocols Used in Outlook Express

A Server is a computer program which serves the request of other programs. It is a running instance of an application. It has the capability to accept requests from the client and give response. A server operates in a client server architecture. When a client gets connected to a server, they communicate through protocols. A protocol is a set of instructions to do a certain task. In email servers, four protocols are used. 

They are POP3 (Post Office Protocol version 3), SMTP (Simple Mail Transfer Protocol), IMAP (Internet Message Access Protocol) and HTTP (Hyper Text Transfer Protocol). Amongst a large number of different email clients, Outlook Express supports all the four protocols. Although, the above mentioned protocols perform a mail function each, but a slight difference can be noticed in their working.


Get Detailed Information About All Mail Servers

1) POP3 Server: It is used to retrieve mail from the server.  It stores email on the server until it is downloaded. The client server deletes the message once it is downloaded. A mail once downloaded will not be opened again on any other system. It provides security to our mail.  In Outlook Express this protocol is followed, but an additional option is provided to ‘leave a copy of the message on the server’. Mails of the POP3 server cannot be recovered easily as there is no copy of the mail on the server. If we need to recover a file from POP3 server, a software will be required to perform the task.

2) SMTP Server: SMTP is a connection oriented protocol. It is used to send emails through the server. It is purely based on ASCII text. It does not deal with the binary files or character. An SMTP transaction consists of 3 command or reply sequences; MAIL (mail), RCPT (recipient), and DATA (data).

3) IMAP Server: They are used to retrieve mail from the server. The mail is permanently stored on the server. Using IMAP server, we can access our mail from any interface. The security level for IMAP server gets a bit degraded as the mail gets permanently stored on the server. However, the brighter side of customizing the settings is that in case email gets corrupted, then we can recover it easily as a copy of it will always be present on the server. 

4) HTTP Server: The HTTP server does not use the undeleted or purge functions. Deleting a message moves the message to the deleted message folder and it can be retrieved from there. It can be retrieved by directly dragging it to the inbox or some other folder. The deleted items get deleted only after a definite or fixed time automatically, also known as the retention period of permanently deleted emails.


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