[Dovecot] Reading the index / log files

Dear Dovecot,

I have a user who claims his mail is being lost. I can find the message marked as having been accepted for delivery in the maillog. I am hoping there is a tool which will let me read his IMAP transactions. We are delivering the messages with procmail and storing them as Maildir files.

I read mail on this very same server and process about 500 mails per day. (Its the machine where all of my mail lists are collected.) I use T-bird, he uses LookOut.

My working theory is that he (or his MUA) is somehow deleting some of his mail. Being able to read a log of his IMAP transactions would be most helpful. I see nothing about this in the Wiki.

Regards, Ray