The user discussion, development and all exciting stuff take place on the mailing list. It's email address is offlineimap-project@lists.alioth.debian.org.

You do NOT need to be subscribed to send emails to this list. Also, you're expected to:

1. keep everyone on the CC list;
2. use the plain TEXT format for your mail (no HTML).

Unfortunately no program is bug free. This is true for all imap servers, and even for OfflineImap. If something goes wrong and you want to report a bug, this is what you should do:

1. If you are using a stable version that came with your distribution, we would appreciate testing to make sure the bug hasn't been fixed already.
2. Starting with version 6.5.0, offlineimap includes an --info switch that will output all kinds of useful information. Do that and capture the information as it will be useful for debugging.
3. Take a debug log of the run that exposes the issue at hand and that does as little as possible otherwise (e.g. by using -f INBOX to only sync the INBOX if that is where your error occurs). You can create a debug log file by using: -d imap -l debug.log (or -d imap,maildir) if you suspect the problem is with how maildirs are handled.
4. This produces a potentially very large log file, including all your IMAP communication. That means that your username and your password will likely be included in the clear in that debug log! Make sure you clean the file from it before sending it in.
5. Do make the file available (if big) or mail it directly to either the mailing list, or -- if your mails contain sensitive information that you don't want to be publically archived -- make them available to a developer of your choice.

AGAIN: Take note that the debug.log will contain passwords and email contents though. So either remove those or make the log available to one of the developers in private if that concerns you.