Log ASN data via default syslog lines

Hi all,

I'm using SpamAssassin 4.0.1 and the ASN plugin, which works as
expected: relying on

  add_header all ASN _ASN_

adds a header like

  X-Spam-ASN: AS200069 Mailjet SAS

Besides, I would like to log such results, ideally via the default
syslog lines, i.e. no additional "asn" debug channel, to make parsing as
easy as possible, to provide ham/spam stats, per ASN.

Is there any possibility to do so, except doing this via "tests hit",
which would require, if my understanding is correct, a specific test,
per ASN?

Thanks a lot in advance,
cheers,
Georg