Amavisd default action isn’t to discard spam
When you install amavisd-new it appears the spam still gets passed on to the sender.
The default action in /etc/amavisd.conf around line 163 is:
# final_spam_destiny => D_BOUNCE;
One would presume based on prior experience with config files that, while it is commented out, that would be the default action. From what I have seen it isn’t. What seems to actually happens is that if ‘$*_quarantine_to’ variable is assigned emails will get delivered there and to the original recipient. Suggesting the D_PASS is the default.
Anyway to fix it, just uncomment and change
# final_spam_destiny => D_BOUNCE;
to:
final_spam_destiny => D_DISCARD;
and restart amavisd service.
Further information:
D_PASS Mail will pass to recipients, regardless of bad contents. If a quarantine is configured, a copy of the mail will go there, if not, at least the recipient received the mail. Note that including a recipient in a @*_lovers_maps is functionally equivalent to setting $final_*_destiny = D_PASS; for that recipient.
D_BOUNCE Mail will not be delivered to its recipients. A non-delivery notification (bounce) will be created by amavisd-new and sent to the sender by amavisd-new. Exceptions: bounce (DSN) will not be sent if a virus name matches @viruses_that_fake_sender_maps , or to messages from mailing lists (Precedence: bulk|list|junk), or for spam level that exceeds the $sa_dsn_cutoff_level. If a quarantine is configured, a copy of the mail will go there. If not, we have lost the mail, but if the mail was legitimate, the sender should receive notification of the disposition of the message.
D_DISCARD Mail will not be delivered to its recipients and the sender normally will NOT be notified. If a quarantine is configured, a copy of the mail will go there. If not, we have lost the mail. Note that there are additional settings available that can send notifications to persons that normally may not be notified when an undesirable message is found, so it is possible to notify the sender even when using D_DISCARD.