SME Server talk:Documentation:User Manual:Chapter2

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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, although IMAP is favoured for almost all situations.

IMAP email, 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.

IMAP allows better overall management of email across a number of end user devices. Whatever you do on one, is reflected to all others, even adding new folders and moving messages to archive folders. eg you can send on a workstation and see all your sent messages on the phone and so on.

Whatever email you send or receive, folder changes etc at any email client including workstations, phones, remote workstations and even webmail (accessed via web browser from home or anywhere), will all show the same. You can set the email clients to retain local copies of messages if that is important.

Drawbacks of IMAP: If you are not connected to a network, new and remote stored email messages are not available to you.(stored emails can be solved with current email clients for desktop - i.e. Thunderbird option to cache the mails for offline working - some clients for mobile devices do this also, practically you'll have the last snapsot from the moemnt when you here online )

POP3 is an earlier and ageing email legacy 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.