Nearly every modern mail server and email client supports both POP and IMAP protocols for transferring email messages to and from an Internet server.
IMAP4 stands for Internet Message Access Protocol version 4. In comparison to email client applications using POP3, email client applications using IMAP4 are relatively more flexible and provide more features. After IMAP4 email applications download email messages onto your computer, a copy of downloaded messages, by default, stays on the email server. Since a copy of all your email messages is present on the email server, you can easily access your email messages even from multiple locations. IMAP4 email allows you to not only access, but also create more than one email folders on the email server.
Thanks to this feature, you need not download every email to check its contents. IMAP4 also supports additional features, supported by majority of IMAP4 applications. For instance, some of the IMAP4 application contain a feature that enables the users to view only the header part (containing the name of the sender and the subject) of their messages. Thus, IMAP4 allows you to download only those messages that you truly want to read.
IMAP4 is also suitable for obtaining non-email data, like documents. Another notable feature of IMAP4 is public folder access.
POP3 or Post Office Protocol version 3 is latest standard protocol designed to receive email messages from an email server. Majority of email service providers furnish POP3 by default and almost all email clients support POP3.
POP3 is a client-server protocol, wherein your email messages are received and stored for you by your server. It deletes all the email messages soon after you download them. It is specifically designed to enable offline email processing.
POP3 is a frequently used e-mail Internet protocol. Once POP3 email applications download email messages from the Internet server onto your computer, all the downloaded messages are removed from the Internet server by default. Due to this, you cannot access your messages from multiple computers or from any other location. However, you can configure some of your POP3 email applications to store or maintain the copies of your email messages on the Internet server. After this, you can access your messages from other locations too. Unlike IMAP4 protocol, POP3 cannot synchronize more than one folder and doesn’t provide any assistance for public folder access.