What is the M3AAWG guidance on content fingerprinting?

M3AAWG guidance on content fingerprinting acknowledges that mailbox providers identify spam patterns through content characteristics. Repeated templates, consistent HTML structures, and predictable elements create fingerprints that filters learn.

When spam campaigns use similar fingerprints, filters block matching patterns. Legitimate senders sharing those patterns may face collateral filtering. This is why avoiding heavily templated designs from shared builders can help.

Best practice involves sufficient template variation that your emails do not match known spam fingerprints while maintaining brand consistency. Unique design elements, varied content structures, and personalization help differentiate your mail from spam patterns.