[Dovecot] Trouble implementing Antispam plug-in for Dovecot

[Ben Johnson]

On 9/11/2012 10:40 AM, Ben Johnson wrote:
> You nailed it, Ben. Thanks!
> 
> I downloaded/installed the dovecot-dev package from the same maintainer
> and was able to build Antispam without issue.
> 
> The hang-up now seems to be with my configuration.
> 
> I'm seeing the following error in my email client whenever I attempt to
> move an email message from, say, Inbox to Junk folder:
> 
> [SERVERBUG] BUG Unknown internal error.
> 
> Nothing at all appears in syslog when this happens.
> 
> I followed the instructions at http://wiki2.dovecot.org/Plugins/Antispam
> , to the letter, I believe.
> 
> The relevant portions of my configuration are as follows:
> 
> ---------------------
> protocol imap {
>   mail_plugins = quota imap_quota antispam
> }
> 
> plugin {
>   quota = dict:user::file:/var/vmail/%d/%n/.quotausage
>   sieve = /var/vmail/%d/%n/.sieve
> 
>   antispam_backend = MAILTRAIN
>   antispam_mail_sendmail = /usr/bin/sa-learn-pipe.sh
>   antispam_mail_spam = --spam
>   antispam_mail_notspam = --ham
>   antispam_spam_pattern_ignorecase = spam;junk
> }
> ---------------------
> 
> The permissions and execute bit are set in accordance with other
> executables in the same directory:
> 
> # ls -lah /usr/bin/ | grep -i "sa-learn-pipe.sh"
> -rwxr-xr-x  1 root root     297 Sep  5 11:17 sa-learn-pipe.sh
> 
> I would provide more log content, but the debug options seem to be gone
> in the forked, >= 2.0 version of this plug-in.
> 
> Any ideas are very much appreciated.
> 
> Thanks,
> 
> -Ben

Given that nobody shared any insight here, I decided to stand-up a
completely new VM with Ubuntu 12.04 LTS and see if the same error occurs.

While the error is different this time around, I am still unable to get
any variant of the dovecot-antispam plug-in working.

When I attempt to use the current packages from Ubuntu 12.04.1 LTS, and
I use the above configuration, my syslog fills-up with the following:

dovecot: imap-login: Login: user=<user at example.com>, method=PLAIN,
rip=10.0.1.57, lip=10.0.1.8, mpid=2879, TLS
dovecot: master: Error: service(imap): child 2879 returned error 3

Surprisingly, I can find only two other mentions of "error 3" anywhere
on the Internet. Those mentions were from another user to this mailing list:

http://www.dovecot.org/list/dovecot/2012-August/067787.html
http://www.dovecot.org/list/dovecot/2012-August/067814.html

The lack of "error 3" ubiquity leads me to believe that I must be doing
something stupid.

There's no question that this behavior is related to the
antispam-plugin, because when I commented-out the relevant lines in
Dovecot's configuration file, the error does not occur.

I have followed the instructions at
http://wiki2.dovecot.org/Plugins/Antispam to the letter, and this is the
result.

The only instance in which I diverged from the Wiki article is that I
used the Ubuntu-provided dovecot-antispam package (instead of compiling
the plug-in from source).

I am trying to use the "mailtrain" back-end, per the above-cited Wiki
article, to call SpamAssassin's "sa-learn" utility for real-time learning.

I am not using the SpamAssassin daemon (spamd).

I'm about to throw in the towel on this plug-in, so any help would be
greatly appreciated.

Thank you,

-Ben