SME Server talk:Documentation:User Manual:Chapter2

IMAP versus POP3 email

There are two common standards for email management, IMAP and POP3. Your server supports both protocols. You will need to select the protocol that is right for your organization.

POP3 is the earlier, better-known email protocol. POP3 was designed to permit on-demand retrieval to a single client machine. Email is stored on the mail server until you retrieve it, at which time it is transferred over the network to your desktop machine and stored in your email box there.

Benefits of POP3: Even when you are not connected to your network, you have access to the email stored on your desktop.

Drawbacks of POP3: POP3 was not originally intended to support users accessing and managing their email from remote systems. Because your email is stored on your desktop, setting up remote access of your email when you are at a different computer can be complex.

IMAP email, in contrast, is designed to permit interactive access to multiple mailboxes from multiple client machines. You manage your email on the mail server over the network. You read your email over the network from your desktop, but the email is not stored on your desktop machine - rather, it is permanently stored and managed on the server.

Benefits of IMAP: You can access all of your new and stored email from any machine connected to a network. Because all employee email is stored on the server, backup of email is easily accomplished.

Drawbacks of IMAP: If you are not connected to a network, new and stored email messages are not available to you.