"Courier-IMAP is a fast, scalable enterprise IMAP server that uses Maildirs."
Support for Courier-IMAP is build into Mail::Toaster. It can be build from FreeBSD ports as well as from sources. Courier-IMAP is very reliable but can be a bother to install and upgrade at times.
Why are IMAP connections getting reset?
See this post to the mailing list for a possible explanation.
Help! I upgraded and now POP before SMTP doesn't work!
As of Courier-IMAP v4.0, the authentication has all moved into courier-authlib. As a result of this seperation, the vpopmail integration that allowed authentication requests to capture the remote IP and allow it to relay is now broken. Thus, IMAP & POP3 before SMTP auth fails.
If you read the courier docs, you'll find they suggest using SMTP-AUTH instead. I agree with them, you should be using SMTP-AUTH on port 587 to relay. However, this does pose a challenge to estabished providers who don't want to require hundreds or thousands of users to change thier email configuration. In such cases, I recommend not using Courier-IMAP for POP3 and use qmail-pop3d instead.
Last modified on 4/28/05.