For a list of currently available IMAP software, see available IMAPsoftware

Click here for a list of differences between MultiNet's and PMDF's POP3 server on OpenVMS.

Tuning your POP and IMAP servers
Why you should not leave mail on server
How not to leave mail on server

Why You Should Not Use the Leave Mail on the Server Option in a POP3 Client

You may see the same messages over and over again.

If the users are pure POP3 users, they will have no way of refiling mail into any folder other than NEWMAIL, when they choose to leave mail on the server. Moreover, the POP3 client does not delete the mail after retrieving it, so they may see the messages over and over again until leave mail on the server is turned off. The only use for this is as a temporary setting when someone has to use another PC on the road. (Note that POP3 ties you up with a particular PC!)

Server performance will degrade

The UIDL command allows the client to keep track of which messages have or have not been read while not deleting them from the server. But, be warned that the mail will be left in NEWMAIL forever and performance will suffer badly because the POP3 server has to read them every time! Thus as more and more messages build up in the NEWMAIL folder, performance will degrade.

How Not to Leave Mail on Server

While you may have no control over what the POP3 client chooses as its preference, you can control what the POP3 server does, in order of effectiveness:

In PMDF V5.0 and later, the default POP3 behavior is to leave the mail in the NEWMAIL folder if the POP3 client did not issue the DELE command to delete the message. Setting the option MOVE_READ_MAIL=1 restores the old PMDF V4.3 behavior of putting read mail (not deleted by the client) into the MAIL folder. Thus, if the user later uses a more capable client (VMS MAIL, PMDF MAIL, an IMAP client, etc.) then they can access the old, read messages in the MAIL folder. If they use nothing but POP3, then this is a waste of your disk space because they can not get at the MAIL folder from POP3.

When you want to outsmart the POP3 client you can also disable the use of the UIDL command in POP3 server with the option NO_UIDL=1, however, most clients now work around this, so it is not very effective.

Our Recommendations in Order of Preference

Use the new popstore technology if the user does not have to have interactive login access. And use the popstore option (in popstore option file) RETURN_AFTER=n (days) to keep message store clean.

Use MOVE_READ_MAIL=1 in the pop3d.cnf option file, so pop user using VMS MAIL will have their read mail moved to the MAIL folder.

Disable the use of UIDL with the NO_UIDL=1 option Tell the users to only use leave mail on the server when they want to get the same mail over again and not as a normal practice. Note that disabling the UIDL command may not always disable the client's capability to leave mail on server.

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