Pigeonhole and duplicate checking

[Dan Ragle]

I spent some time setting up Dovecot LMTP with Pigeonhole this weekend. 
I got most of the things I wanted to working but have a few issues that 
I'm hoping that someone might be able to help with.

First, I'm running the stock version of the tools from the core repos 
for CentOS/6, which means Dovecot 2.0.9 and Pigeonhole 0.2.2. 
Unfortunately, I don't expect to be able to upgrade those anytime soon, 
so I'm hoping I can find workarounds for my existing versions.

My mailserver is sendmail, I linked to Dovecot LMTP by adding:

     FEATURE(`local_lmtp', `[IPC]', `FILE /var/run/dovecot/lmtp')dnl

to my sendmail.mc.

In my prior procmail setup, I auto-forwarded all my SPAM E-mail to a 
separate user on the system with their own account (called spamuser). In 
the Pigeonhole setup it looks like I have to redirect those messages 
(i.e., redirect "spamuser at mydomain.com";). That works, but I'm having 
issues with "duplicate" messages getting delivered directly to my inbox 
instead of getting redirected. IOW, my regular user's .dovecot.sieve has:

     if header :contains "X-Spam-Flag" "YES" {
         redirect "spamuser at mydomain.com";
         stop;
     }

and the spamuser's .dovecot.sieve has:

     require ["imap4flags"];
     setflag "\\seen";

(this system is entirely for personal use, no concerns with a user's 
Spam being seen via the separate spamuser account).

Now, the problem I'm having is that sometimes a message arrives with a 
duplicate message-ID. Here's an abbreviated example from my maillog:

   Feb 15 00:30:46 myhost sendmail[26844]: u1F5UeBP026844: 
from=<ciuehazt at autoonecareers.com>, size=613, class=0, nrcpts=1, 
msgid=<68895654496651-HLTYGGRLPDJDVTZRHFIKGAON at hverovvxzb.arkansas-email.com>, 
proto=SMTP, daemon=MTA, 
relay=117.27.191.61.broad.static.hf.ah.cndata.com [61.191.27.117] (may 
be forged)
   Feb 15 00:31:05 myhost dovecot: lmtp(26856): Connect from local
   Feb 15 00:31:07 myhost sendmail[26867]: u1F5UvFi026867: 
from=<ciuehazt at autoonecareers.com>, size=613, class=0, nrcpts=1, 
msgid=<68895654496651-HLTYGGRLPDJDVTZRHFIKGAON at hverovvxzb.arkansas-email.com>, 
proto=SMTP, daemon=MTA, 
relay=117.27.191.61.broad.static.hf.ah.cndata.com [61.191.27.117] (may 
be forged)
   Feb 15 00:31:10 myhost dovecot: lmtp(26856, dmr): 
7Hj/LoBiwVboaAAACXJZQA: sieve: 
msgid=<68895654496651-HLTYGGRLPDJDVTZRHFIKGAON at hverovvxzb.arkansas-email.com>: 
forwarded to <spamuser at mydomain.com>
   Feb 15 00:31:10 myhost dovecot: lmtp(26856): Disconnect from local: 
Client quit
   Feb 15 00:31:10 myhost dovecot: lmtp(26893): Connect from local
   Feb 15 00:31:10 myhost dovecot: lmtp(26893, spamuser): 
9TPnN55iwVYNaQAACXJZQA: sieve: 
msgid=<68895654496651-HLTYGGRLPDJDVTZRHFIKGAON at hverovvxzb.arkansas-email.com>: 
stored mail into mailbox 'INBOX'
   Feb 15 00:31:11 myhost dovecot: lmtp(26893): Disconnect from local: 
Client quit
   Feb 15 00:31:18 myhost dovecot: lmtp(26893): Connect from local
   Feb 15 00:31:18 myhost dovecot: lmtp(26893, dmr): 
+TPnN55iwVYNaQAACXJZQA: sieve: 
msgid=<68895654496651-HLTYGGRLPDJDVTZRHFIKGAON at hverovvxzb.arkansas-email.com>: 
discarded duplicate forward to <spamuser at biblestuph.com>
   Feb 15 00:31:18 myhost dovecot: lmtp(26893, dmr): 
+TPnN55iwVYNaQAACXJZQA: sieve: 
msgid=<68895654496651-HLTYGGRLPDJDVTZRHFIKGAON at hverovvxzb.arkansas-email.com>: 
stored mail into mailbox 'INBOX'

So the first message comes in and is redirected properly to my spamuser 
and stored in the inbox. The second one comes in, pigeonhole sees it's a 
duplicate, refuses to redirect it, and stores it in my inbox instead.

I tried forcing the .dovecot.lda-dupes file to be a symlink to /dev/null 
just to see if it would work, but unfortunately dovecot just recreates 
it as a normal file the next time it delivers to that user.

Ideally, I'd like to just discard the duplicates. It looks like there is 
duplicate testing functionality available, but not until later versions 
of Dovecot/Pigeonhole.

Is there anyway I can either just discard the duplicates, or get them to 
be redirected to the spamuser?

Also, some other questions I came up with along the way:

Is there any way I can force a message to fileinto a different user's 
Mailbox? I'm guessing no since it appears that the lmtp drops root 
privileges before the global sieve script is interpreted, but thought 
I'd ask anyway. I did try:

     fileinto "/var/mail/spamuser";

But Dovecot complained, something about the mailbox pattern being 
invalid. If it were possible, I would think it would want something like

     fileinto "spamuser:INBOX";

instead, but I don't know if that is even possible.

In a global sieve script, is there anyway to know/test which system user 
is the targeted user for delivery? So in a global sieve_before script I 
could test the target user, and if it's spamuser just file it 
immediately and stop with no further testing?

Thanks for any assistance!

Dan