[Dovecot] File isn't in mbox format - Couldn't open INBOX

[Stephen K. Gielda]

At 10:03 AM 4/14/2005, Rich West wrote:
>While I saw another thread on the list similar to the issue I was 
>experiencing 
>(http://dovecot.org/pipermail/dovecot/2005-February/006168.html), I was 
>wondering if there was a way around this problem (the thread simply 
>suggested upgrading, but are the later version (specifically the 1.0-test 
>releases) ready for prime time?)...
>
>We're periodically having this with some users (not sure what client they 
>are using, but I am pretty sure it is MS Outlook) where the inbox is in 
>near perfect shape except for some extra characters at the beginning of 
>the file.  POP or IMAP delivery fails with an error stating "File isn't in 
>mbox format - Couldn't open INBOX".  It looks like those characters are of 
>a previous message that was not completely removed from the file, and 
>those characters seem to throw everything out of wack..
>
>It's easily correctable by removing the bogus characters from the 
>beginning of the file, but that gets annoying quickly..

I see it too.  You running procmail by any chance?  In our case it appears 
to be due to file locking, with procmail grabbing the mail spool while the 
user is deleting messages.  Not sure if it is procmail specific or not, but 
the client doesn't seem to matter as it happens with pretty much all of them.

/steve