What is the M3AAWG Sender Best Common Practices document?
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You've probably seen M3AAWG referenced in a deliverability blog post or a certification program's requirements. But what is it actually, and does it matter to you as a sender?
M3AAWG stands for the Messaging, Malware and Mobile Anti-Abuse Working Group. It's a nonprofit industry body made up of major ISPs, ESPs, security companies, and anti-spam researchers who meet to figure out how to fight abuse at scale. Think Gmail, big hosting companies, and the people who run blocklists, all in one room.
The Sender Best Common Practices (SBCP) document is what that group publishes as their shared view on how legitimate senders should behave. It covers things like authentication setup, list management, bounce handling, complaint processing, and unsubscribe practices.
Here's the thing most people miss: it's not a certification program. Following it won't get you a badge or a whitelist entry. It's more like a consensus document from the people who actually decide what happens to your email. When M3AAWG says something is a best practice, that's not opinion. It's the ISPs and anti-abuse teams telling you what they want to see.
That said, you don't need to read the whole document to benefit from it. Most of what's in there shows up in the requirements for programs like CSA certification, your ESP's sending policies, and Google and Yahoo's bulk sender requirements. If you're already following those, you're already aligned with most of M3AAWG's guidance.
If you want to go straight to the source, the SBCP document is free on the M3AAWG website. It's dense but worth skimming if you're building out a sending program from scratch or troubleshooting a reputation problem.
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