ox.ac.uk email security: SPF, DKIM & DMARC

Recommendations

1. 1Upgrade your DMARC policy from p=quarantine to p=reject for full blocking▾

   With p=quarantine, spoofed emails are sent to spam instead of being blocked outright. Some recipients still check spam folders, and sophisticated attacks can be flagged as legitimate by users. p=reject ensures fraudulent emails never reach any folder.

2. 2Add rua=mailto:dmarc@yourdomain to your DMARC to receive reports▾

   Without DMARC reporting (rua=), you have no visibility into who is sending email on behalf of your domain. Aggregate reports let you detect spoofing attempts, identify misconfigured legitimate senders, and confidently tighten your policy over time.

3. 3Harden 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.

4. 4Add 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.