Spamjadoo
Notes from the mail queue
Written by the engineers who run the gateway. Every article opens with the answer, then shows the work.
- SMTP-Level Filtering vs Content Filtering
SMTP-level filtering decides whether to accept a message during the SMTP conversation, using facts about the connection, sender and recipient, and refuses with a 5xx error before the message body is transmitted. Content filtering accepts the whole message first, then scores its contents. The first is cheaper, gives the sender a reason, and produces no quarantine; the second is needed for the mail that passes the first.
10 September 2026 · Spamjadoo engineering
- DMARC Explained: The Complete Guide
DMARC is a DNS record that tells receiving mail servers what to do when a message claiming to be from your domain fails both SPF and DKIM alignment, and asks them to send you reports about it. Published at _dmarc.yourdomain, it is the only standard that lets a domain owner say: refuse mail that pretends to be me.
10 September 2026 · Spamjadoo engineering