Mail relays - Part 2 | Problems with forwarded mail?

This guidance recommends mitigating forwarding-related spam problems by enforcing robust SMTP-time spam filtering, validating forwarding destinations via tokenized confirmation, limiting forwarder counts, rewriting envelope senders (e.g., SRS) to preserve SPF/DKIM authentication, avoiding sending bounces for unauthenticated mail, proactively monitoring mail server logs, and signing forwarded mail with the customer's domain via DKIM to protect IP reputation.