Introduction to IMAP4 for VPOP3 users
IMAP4 is the latest Internet email protocol. It is currently supported by only a few email servers
(including VPOP3 Enterprise) and a few modern email clients (such as Microsoft Outlook Express, Netscape Messaging,
Eudora Pro 4.2 etc).
IMAP4 can be used as a replacement for the more well known POP3 protocol. The main difference between the
two protocols is that with IMAP4 the messages are stored and manipulated on the email server and with POP3 they are
downloaded to the email client and stored and manipulated there.
This change in approach means that IMAP4 requires more work from the mail server and requires much more
disk space on the server, but it means that users can share mailboxes and change PCs whilst still having
access to their email.
IMAP4 is not really designed for offline working (POP3 was designed for that), but some email clients
do support synchronisation with an IMAP4 mail server, but the efficiency of this varies depending on the
way the email client works, so check it is suitable before committing yourself to it.
Using IMAP4 you can organise mail into 'folders' on the server, mark messages as read, perform searches on
the server etc.
To make a VPOP3 Enterprise users access their mail using the IMAP4 protocol instead of the POP3 protocol,
simply change the email client software to use IMAP4 instead of POP3. You can change back and forth between
the two protocols at will. You should see the documentation for your email client to see how to change the
protocol type.
If the user uses the POP3 protocol they will only be able to see the INBOX IMAP4 folder.
If a user uses the 'Web Mail' interface to VPOP3, they will be able to see all the IMAP4 folders
and vice versa.
Folder Access Restrictions
VPOP3 supports the "Access Control List" (ACL) extension to IMAP4. This allows users/administrators
to specify which users can read/write/modify/etc the messages in an IMAP4 mailbox. Using this system you can
set up shared mailboxes which only certain people can modify, but other people can read.
You can modify the ACL settings using a suitable email client (the only one we have found which works is
Mulberry), or by using the 'Web Mail' interface in VPOP3.
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