Delays in mail deliveries

[Damian]

> smtp-amavis unix -      -       n       -       2       lmtp

maxproc does not match $max_servers.

>      -o smtp_data_done_timeout=1200
>      -o smtp_send_xforward_command=yes

These are the wrong options for an lmtp service. This is why you see:

> client IP address unknown, fetched from Received: 127.0.0.1
Beyond that, delays of 120s and 300s look suspiciously man-made. I don't have a concrete idea, though. This may be a question for 
postfix-users (together with related logs from vmail2).