As we know that SMTP is used to deliver the mail to a user's mail box. Then users need to access their respective mail boxes to access the mail. This access of mail box by user is done with the help of POP and IMAP protocols. We will see difference between IMAP version 4 and POP version 3.


Post Office Protocol version 3 i.e. POP3 is used as message retrieval protocol to access internet based email account. It is described in RFC 1939. Client initiates TCP connection to POP3 server on port 110. Once the connection is established client send both username and password information to the server, once this gets validated user can access the mailbox. POP3 client sends 4 character commands to the server. Server responds small no. of alphabetic responses.All these commands and responses are not visible to the email user.

With POP3 user can delete and download the mails. User can also list the mails. But user can not alter or change the contents of the email on the server. To do so, user need to first get the contents on local client machine and then modification can be done. This causes delay and also increases network traffic due to content downloading function.


IMAP4 stands for Internet Message Access Protocol version 4. IMAP addresses the limitation of POP3 and it allows various functions such as move,delete and view messages without even copying the contents on the local machine. Hence the major difference is that POP3 helps download the contents and then operate on the contents on client machine locally, while IMAP4 helps operate on the contents directly in the server without downloading to the local machine.


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