[Dovecot] Duplicate E-mail Problem

[Phillip T. George]

Timo Sirainen wrote:
> On Fri, 2007-04-13 at 09:10 -0500, Phillip T. George wrote:
>   
>> Anyway, I'm having a problem, that may or may not be related to 
>> Dovecot.  Specifically, duplicate (and sometimes triplicate) emails are 
>> appearing.  These emails have exactly the same queue ID, so its not that 
>> they were sent multiple times.  These dup emails do not show up to me ever.
>>     
>
> What kind of filenames do they have in maildir? Do you see anything in
> Dovecot's error logs? The only reason why Dovecot would internally
> duplicate messages is if it detects multiple filenames with same base
> name, which aren't hardlinks to each others. And that could happen if
> the maildir filenames aren't truly unique. You said you're using
> Procmail, are you sure you're not using MH filenames
> (http://wiki.dovecot.org/MailboxFormat/Maildir)?
>
> If that's not the problem, you can enable mail_log plugin and check if
> it logs that the client does a duplicate COPY.
> http://wiki.dovecot.org/Plugins/MailLog
>   

Ok.  Using the logging, I saw 2 entries today:
Apr 16 12:51:45 east dovecot: IMAP(user.domain.com), IP(70.177.64.93): 
copy -> Spam: uid=718, msgid=<sameid at domain.com>
Apr 16 12:51:45 east dovecot: IMAP(user.domain.com), IP(70.168.68.56): 
copy -> Spam: uid=718, msgid=<sameid at domain.com>

It appears that the problem is that the user has two email programs 
running the same filters at the same time.  Somehow, this creates a 
duplicate message.  Any clues as to why this might be?  Are there any 
options that may cause this behavior to change?  I thought maybe the 
options "maildir_copy_with_hardlinks" and/or 
"maildir_copy_preserve_filename" may be helpful options...(they're both 
set to the default of 'no').

Any recommendations?

Thanks,
Phillip