[Dovecot] hardluck w/ sieve

[errno]

I've followed the docs here:

http://wiki.dovecot.org/LDA/Sieve/Dovecot

... in particular, the 'Per-user Sieve script location' scenario.

However, I'm unable to get any behavior that indicates that
sieve is functioning correctly - well, functioning _at_all_ would
be more accurate.

Relevant dovecot.conf:

protocol lda {
  ...
  mail_plugins = sieve
}
auth default {
  ...
  passdb passwd-file {
    args = /var/vmail/passwd
  }
  userdb static {
    args = uid=vmail gid=vmail home=/var/vmail/%d/%u
  }
}
plugin {
  sieve = /var/sieve-scripts/%d/%u.sieve
}


ls -l /var/sieve-scripts/domain.com/user.sieve
-rw-r--r-- 1 vmail vmail 224 May 22 00:18 /var/sieve-scripts/domain/user.sieve


I of course have an extremely simple rule in the example 'user.sieve' file; but 
for whatever reasons, no filtering is occurring. 

Is there anything obvious in my configuration that's broke? How best to
debug?


Thankyou!