Consider integrating RSpamd

[springcomp]

RSpamd is an industry-standard SPAM solution that integrates into many MTAs, including Postfix.

Benefits:

• Provides SPAM score to classify / reject emails.
• Can check DKIM signature.
• Can check SPF policies.

It’s not clear (to me) if SimpleLogin already checks DKIM signature from incoming email.
My analysis seems to indicate that this is not the case.
simple-login/app#2637

Actions:

• You may consider moving DNSBL checks from Spamhaus to RSpamd instead.