Email Security Analysis of heise.de

Recommendations

1. 1Change your DMARC policy from p=none to p=reject to block spoofing▾

   With p=none, your DMARC record only monitors — it doesn't actually block spoofed emails. Attackers can still send emails as your domain and they'll be delivered normally. Switching to p=reject instructs receiving servers to drop fraudulent messages before they reach the inbox.

2. 2Harden your SPF by replacing ~all with -all (hardfail)▾

   With ~all (softfail), unauthorized senders are flagged but emails are usually still delivered. Switching to -all (hardfail) explicitly tells receiving servers to reject emails from unauthorized sources, providing much stronger protection against spoofing.

3. 3Add MTA-STS to enforce TLS encryption for incoming emails▾

   Without MTA-STS, an attacker performing a man-in-the-middle attack can downgrade the connection between mail servers to plaintext, intercepting emails in transit. MTA-STS tells sending servers to only deliver via TLS with a valid certificate, preventing downgrade attacks.