[Dovecot] When should dictionary entries for the expire plugin be added/updated?

[Ralph Seichter]

I've set up Dovecot 2.0 with the expire plugin using an SQLite DB, and
when mail is delivered via dovecto-lda, the DB gets updated as expected.
However, when I use Thunderbird 3.1.2 for Mac OS X to move a message to
any of the folders known to the expire plugin (e.g. the 'tmp' folder),
the SQLite DB is not updated.

Here is an excerpt of my current configuration:

  # /etc/dovecot/dovecot.conf
  dict {
    expire = sqlite:/etc/dovecot/dict-expire.conf
  }
  plugin {
    expire = Junk
    expire2 = Trash
    expire3 = tmp
    expire4 = *.News
    expire5 = *.Reports
    expire_dict = proxy::expire
    sieve = /etc/dovecot/sieve/%u.sieve
  }
  service dict {
    unix_listener dict {
      # Ensure that there is no permission-related problem
      mode = 0666
    }
  }
  protocol lda {
    mail_plugins = expire sieve
    postmaster_address = postmaster at domain.tld
    sendmail_path = /usr/sbin/sendmail
  }

  # /etc/dovecot/dict-expire.conf
  connect = /var/lib/dovecot/expires.sqlite
  map {
    pattern = shared/expire/$user/$mailbox
    table = expires
    value_field = expire
    fields {
      username = $user
      mailbox = $mailbox
    }
  }

  # Schema dump of /var/lib/dovecot/expires.sqlite
  PRAGMA foreign_keys=OFF;
  BEGIN TRANSACTION;
  CREATE TABLE expires (
    username VARCHAR(75) NOT NULL,
    mailbox VARCHAR(255) NOT NULL,
    expire integer NOT NULL,
    PRIMARY KEY (username, mailbox)
  );
  CREATE TRIGGER mergeexpire BEFORE INSERT ON expires FOR EACH ROW
  BEGIN
    UPDATE expires SET expire=NEW.expire
      WHERE username=NEW.username AND mailbox=NEW.mailbox;
    SELECT RAISE(IGNORE)
      WHERE (SELECT 1 FROM expires WHERE username=NEW.username AND mailbox=NEW.mailbox) IS NOT NULL;
  END;
  COMMIT;

With these settings, rows will be inserted to (or updated within)
expires.sqlite when dovecot-lda stores messages to any of my "Reports"
folders using sieve rules. When I manually move messages to "tmp" or
"Junk", the database remains unchanged. Also, when I delete messages in
Thunderbird, I'd expect database additions for the folder "Trash", but
this does not happen either. What am I doing wrong here?

-Ralph