[Dovecot] Error in Thunderbird

I received a mail, Thunderbird was supposed to move that mail in a folder, according to its filter rules, but appeared this popup:

http://luigi.rosa.name/dovecot1.gif

The log entries are:

Dec 14 07:23:07 mail dovecot: IMAP(lrosa): Fixed index file /var/spool/mail2/lrosa/.HT list/dovecot.index: first_recent_uid_lowwater 839 -> 838

Dec 14 07:23:07 mail dovecot: IMAP(lrosa): Corrupted index file /var/spool/mail2/lrosa/.HT list/dovecot.index: Duplicate header extension keywords

The file http://luigi.rosa.name/dovecot1.tgz contains the dovecot files I found in the folder "HT list" (no problem about privacy: the archives of that mailing list are public).

Ciao, luigi

-- / +--[Luigi Rosa]-- \

There ain't no such thing as a free lunch.