#40 dovecot: forward via LMTP and sieve

[tomop]

Hi.

This patch will be able to detect forwarding via dovecot LMTP and sieve.

Example:
dovecot: lmtp(14141, foo@example.com): vOvMEzhDhlQ9NwAApEFlZQ: sieve: msgid=043fa4c4c461fd6ccaeb801f12a6bdfae001392d@bar@example.net: forwarded to baz@example.com