dovecot - Nov 2005 - Mailbox isn't a valid mbox file

Hello all,

I have a new installation of Fedora 4 and Dovecot 1.4.Alpha4

A small percentage of my users are getting unable to pop mail from a client
(ie:  Outlook), they get continually prompted for username/password.  The
error they get is:  Mailbox isn't a valid mbox file.

When I look in the file, I don't see anything unusual.  There's not much
info on the Internet about this problem.  The only thing I found mentioned
blank lines in the file.  So, I tested and found that I'm able to get mail
on other accounts regardless of whether there are blank lines in between
messages.

Thanks,

Cliff

Greetings Dovecot folks,

We're having a version of this issue too, also with Fedora Core 4.
We were first having it with the provided 0.99 release of Dovecot 
provided by Fedora, but have since built Dovecot 1.0Alpha4 from source, 
but we're still seeing a version of this issue (and corrupted 
Netscape/Thunderbird .msf files too but this is likely a separate issue).

In dovecot.conf we have turned on the option that scans for changes done 
by outside programs (since a lot of our users check email from home as 
well) and that seemed to help, but it is not entirely fixed.

Our version of the problem that Cliff is referring to is that in the 
mbox format mailbox that is corrupted, there is the tail of another 
email (like 1-3 lines of it) just before the "From " line that should
be
the first line.  Hand editing the email box and removing the offending 
lines fixes the problem, but I'm wondering how to approach this.  Is it 
a file locking problem?

Thanks for any insights,

Ellen Clary
Senior System Administrator
Dynamic Graphics
ellen at dgi.com

Cliff Hayes wrote:
>Hello all,
>
>I have a new installation of Fedora 4 and Dovecot 1.4.Alpha4
>
>A small percentage of my users are getting unable to pop mail from a client
>(ie:  Outlook), they get continually prompted for username/password.  The
>error they get is:  Mailbox isn't a valid mbox file.
>
>When I look in the file, I don't see anything unusual.  There's not
much
>info on the Internet about this problem.  The only thing I found mentioned
>blank lines in the file.  So, I tested and found that I'm able to get
mail
>on other accounts regardless of whether there are blank lines in between
>messages.
>
>Thanks,
>
>Cliff
>  
>

--On Wednesday, November 16, 2005 10:55 AM -0600 Cliff Hayes 
<chayes at afo.net> wrote:
> When I look in the file, I don't see anything unusual.  There's not
much
> info on the Internet about this problem.  The only thing I found mentioned
> blank lines in the file.  So, I tested and found that I'm able to get
mail
> on other accounts regardless of whether there are blank lines in between
> messages.
Generally the problem is that the file doesn't start with "From ".
The
"blank lines" are before these 5 characters. I've seen this issue
come up
periodically in one user's Mozilla Trash folder. Nothing writes to that 
folder except her IMAP client, and she runs only one instance. 
(dovecot-0.99.13-4.FC2) Each time, the problem has been a few thousand 
ASCII NUL's at the beginning of the file. I delete those and the system 
works fine for a few more weeks. At some point I'll update to the 1.0 
branch, which has different mbox code.