Description of problem:

I have been bitten by the problem described in link below, rather quickly after
installation of dovecot I must say. 

I use dovecot and Thunderbird. Thunderbird accesses mail through SSL-ed IMAP.
MTA is postfix. We have mbox format (gonna be changed soon). 

So, at 

http://blog.tcg.com/tcg/2007/02/dovecot_invalid.html

we read:

"Though working for a long time, while trying to read their mail, two of our
Thunderbird IMAP users suddenly received the error: "The current command did not
succeed.  The mail server responded: Invalid messageset: -2147483648:*."

A bit of research revealed that Dovecot versions 0.99.13 and earlier have an
interesting bug in which the X-UID header for emails can get too large, and
therefore cannot be processed by Dovecot."

This is difficult to reproduce, but the fix is in. Suppose the user is
"mail-0214", then we just need to filter the X-UID and X-IMAPbase headers out of
the INBOX (or some other affected mbox file), then something similar to this
will help:

cp mail-0214 mail-0214.bak
/etc/rc.d/init.d/dovecot stop
cat mail-0214.bak  | grep -v '^X-UID: ' | grep -v "^X-IMAPbase: " > mail-0214.new
/bin/cp mail-0214.new mail-0214
chmod 600 mail-0214 && chown mail-0214:mail mail-0214
/bin/rm -rf mbox_mail-0214/.imap/INBOX
/etc/rc.d/init.d/dovecot start