Amavisd listening on multiple UDP ports

[Damian]

>   COMMAND PID  USER  FD      TYPE               DEVICE           SIZE/OFF    NODE NAME
>   perl  79714 vscan 10u IPv4 0xfffff80164e96b40      0 UDP $amavis.ip:59511->$nameserver.ip:53
>   perl  79714 vscan 12u IPv4 0xfffff802071cb880      0 UDP *:47998->*:*

Very interesting. In my tests, the second line (listening socket) is the result of Amavis' DKIM verifier, while the first line is 
spawned by SpamAssassin. The listening socket is used only until SpamAssassin has been loaded by the first mail which does not 
bypass spam checks, because SpamAssassin overrides the `persistent_udp` option initially set to `1` by Amavis.

> Is there any way to disable these (random?) UDP listening ports

There is no Amavis confvar for the `persistent_udp` option. You would have to modify the executable.