Delays in mail deliveries

[Damian]

> However, it still takes time (up to 10 minutes) for final delivery, 
> because there is a mail processing queue in which the mail has to 
> enter, be examined (even minimally) and be returned. Amavis is taking 
> time because clamd scan is time consuming and it is processing mails 
> which are ahead (in queue) of the mail we want to expedite.

As Bastian pointed out, your mail sample passed Amavis within a few 
seconds. If those received timings are typical for your problem, forget 
about micro-optimizing Amavis.