14: Competent Spammers

60 Seconds of WIP · Sep 28, 2023 · 1m

Here’s a few words on the Sender Policy Framework, aka SPF, aka omg why please no no no.

SPF is often touted as an anti-spam measure. It isn’t. It’s one component of a spam assessment policy. Competent spammers are among the most reliable publishers of SPF records, gleefully declaring that any host may send mail for their domains. Emails from domains without SPF records are likely to be classified as spam, however.

When a MTA with basic spam protections receives an email, it performs an SPF check against the sender in the envelope. This is the email address used in the SMTP exchange’s…