What’s the difference between a standard, a best practice, and a recommendation?
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You've probably read email advice that uses these three words interchangeably. They're not the same thing, and knowing the difference actually matters when the guidance you're reading starts to conflict.
A standard is a formal specification with broad industry consensus. RFC-defined protocols like SMTP, SPF, and DKIM are standards. Deviating from them doesn't just hurt your deliverability. It breaks compatibility with other mail servers entirely. Standards define how things must work.
A best practice is a proven approach that experienced practitioners agree produces good results. M3AAWG documents are full of best practices. Following them improves your outcomes, but no server will reject your email just because you skipped one. Best practices define how things should work.
A recommendation is more contextual guidance. It might work well in certain situations but doesn't apply universally. Think of it as advice worth considering, not a rule worth enforcing.
When advice conflicts, the hierarchy is clear. Standards win, always. If a best practice contradicts a standard, the standard takes priority. If a recommendation conflicts with a best practice, lean toward the best practice (and ask why the conflict exists in the first place, because that's usually where the interesting nuance lives).
If you're unsure whether something you've read is a standard, a best practice, or just an opinion, our SOS hotline is free and we're happy to help you sort it out.
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