[Dovecot] Mbox corruption - Inbox beginning with 'FFrom' or 'FrFrom'

Erik Kratzenberg erik5 at pair.com
Tue Jul 20 15:42:20 EEST 2010

I experienced this today with my own IMAP folder, so maybe being able to 
offer a more specific order of events will help.  Also not sure if I 
previously mentioned that this is occasionally happening with IMAP 
folders even though it's much more common under POP3.

1) I had just cleaned out my Junk folder.
2) Two messages were received without error.
3) I marked the folder as read in Thunderbird.
4) I restarted Thunderbird
5) The next delivery attempt to that mailbox (using dovecot deliver)

    save failed to Junk: Mailbox isn't a valid mbox file

The odd thing is that the delivery *did* succeed because that message is 
in there.  The very first message header is the one that was corrupted 
which always seems to be the case.  Does "deliver" read/write the entire 
mbox file or just append the new message to the end?

On 06/08/10 11:24, Erik Kratzenberg wrote:
> We've had situations where the same user will have their mailbox
> corrupted 2 or 3 times a day.
> We're not using filesystem quotas and nothing but Dovecot is writing to
> these mailboxes.
> We've been pushing people to switch to IMAP which seems to be the only
> solution so far. That's decreased the number of reports we're getting,
> but they're definitely still coming in.
> On 05/25/10 15:10, Timo Sirainen wrote:
>> On Fri, 2010-05-07 at 15:03 -0400, Erik Kratzenberg wrote:
>>>>>>> -Dovecot.log : Mar 29 11:00:06 Error: POP3(user_login):
>>>>> > > Couldn't init INBOX: Mailbox isn't a valid mbox
>>>>> > > -The mailbox start with either 'FFrom or 'FrFrom'
>>> It's happening several times a day, sometimes to the same mailbox.
>> How often does the same user get the error?
>>> We also noticed some other storage and assertion errors around the same
>>> time the corruption occurs which may or may not be related:
>>> Mar 26 14:49:36 dovecot: Panic: POP3(user at home.com):
>>> file mbox-sync.c: line 1314 (mbox_sync_handle_eof_updates): assertion
>>> failed: (offset == 0|| offset> 31)
>> There's a good chance this is related.
>>> Mar 24 15:21:59 dovecot: POP3(user at home.com): Cached
>>> message offset 2 is invalid for mbox file
>>> /usr/boxes/mailbox
>> Are you using filesystem quota for users? That might explain this.
>> Otherwise, the above shouldn't be happening if Dovecot is the only
>> software writing to the mbox files..
>>> I'm not sure if "mail_debug=yes" will give us any additional info, but
>>> I'm turning that on now.
>> No, that won't log anything useful.

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