[Dovecot] Multiple copies of a message

[Benjamin R. Haskell]

On Tue, 29 Jan 2008, Anne Wilson wrote:

> I have a problem and I don't know which part of the mail chain could be
> causing it, although dovecot does seem to be the most logical source.
>
> I get multiple copies of messages to my Inbox.  I have just deleted 24 copies
> of a newsletter from Computer Shopper.  The worst example I have seen of this
> had more than 90 copies.  This doesn't happen to any subfolder of Inbox, just
> Inbox itself.
>
> The problem started about 10-14 days ago, on the old mail server (running
> Mandriva 2007.1).  The new server runs CentOS and exhibits the same problem.
>
> I'd be interested in any comments, as my efforts to track it down have got
> nowhere.
>

Are you using Dovecot's 'deliver' as your LDA (local delivery agent)? 
Otherwise I'd suspect the problem lies in whatever you're using for your 
local deliveries, creating some kind of mail loop. Check your 
.forward/.qmail/.procmail/whatever files. I haven't heard of/seen dovecot 
duplicating messages unless there are actually multiple copies in your 
mailbox.

If your LDA isn't already doing so, add a 'Delivered-To' or 'X-Mail-Loop' 
header at each stage, so you can more easily tell if this is what's 
happening. And then (I assume you've done this, but it should be said) 
look at the headers of the duplicated messages to see if they're 1) 
actually distinct messages [external problem] 2) being delivered multiple 
times

Best,
Ben