I've noticed that a lot of connections from spammers trying to send mail
to local users claiming the sender is another local user.
So I want to check that if sender domain name is in sender_local_domains
the user must be authenticated or host must be in relay_from_hosts.
Does this look correct?
acl_smtp_mail:
# Accept all authenticated connections
accept authenticated = *
# Accept all local hosts
accept hosts = +relay_from_hosts
# Deny if sending host claims to be a local user
deny sender_domains = +sender_local_domains
message = Fake sender address
# Accept all other
accept
