Folks -

I just ran across this problem; not sure how it originally happened.

I noticed that Thunderbird was displaying the wrong message body when I selected a message. I tried several actions to clean up the problem (stopping dovecot and thunderbird, removing all .thunderbird/pref/ImapMail cache data, removing all dovecot index and uidlist files), to no avail. Then I noticed that somehow a core file had made it into my main inbox. I surmise that dovecot saw it as a legitimate email but thunderbird refused to count it (or some permutation thereof). (The core file had been renamed "core,2u" IIRC). Anyway, removing the offending file and (again) all cache files seems to have solved the problem.

Just FYI.

-- Mario