Dovecot (on Mac OS X Server 3 - Mavericks) giving “Error: Failed to autocreate mailbox INBOX: Permission denied”

I recently upgraded my server to Mavericks and I thought everything had gone perfectly. As it turns out, that was not exactly the case. After everything working fine for a week or so, I created a new user and my mail server flat out stopped working. Most frustratingly, there were no log errors (in any of the many mail logs) which shed any light on the cause.

After much trial and error, I finally got my mail server functioning (partially) by reinstalling server and restoring the mail folder from the previous day's backup (yay for backups). However, as is often the case, there were MANY permission issues. After slogging through various permission problems, I believe that my system is now receiving mail, however none of my users can check it because every time someone attempts to login the server generates following error:

Error: Failed to autocreate mailbox INBOX: Permission denied

I would assume that this is yet another permissions problem, however after much searching, I still cannot resolve this. To be clear, I don't want Dovecot to autocreate any mailboxes at this point because all of the mailboxes should exist.

Any help on this would be sooooooo greatly appreciated.

P.S. On a side note: why is it that repairing permissions never takes care of difficult issues like these? That would be awfully helpful...