What’s the difference between “message too frequent” vs “policy violation”?
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You send a campaign and two bounces come back with different error messages. One says something like "message too frequent" and the other says "policy violation." Both stopped your email from delivering, but they mean completely different things and need completely different fixes.
"Message too frequent" is a rate-based rejection. The receiving server is telling you that you're sending too fast or too much, and it needs you to slow down. This comes back as a rate control signal, typically with a 4xx SMTP code, which means it's temporary. The server isn't rejecting you permanently. It's telling your sending system to back off and try again later. If you slow your sending speed and spread your volume over a longer window, the messages will usually get through on a retry.
"Policy violation" is a rules-based rejection. The receiving server checked your email against its own policies and decided something was wrong with it. This one is more serious. It often comes back with a 5xx SMTP code, which means the server is refusing the message outright and won't accept a retry without a fix.
What can trigger a policy violation? A few common causes:
- Authentication failure. Your SPF, DKIM, or DMARC didn't pass
- Content policy breach. The message tripped a content filter (links to flagged domains, spam-like formatting, missing required elements)
- Ignored opt-out. You emailed someone who had previously unsubscribed or reported you
- TLS requirement not met. The receiving server requires an encrypted connection and yours didn't provide one
The core distinction is this: rate issues fix themselves if you slow down. Policy violations don't. You have to find the actual cause and resolve it before that server will accept your mail again. (Waiting longer won't help if you're hitting a hard rule.)
If you're seeing policy violations around authentication, that's usually the fastest thing to investigate first. A broken SPF record or a missing DKIM signature can trigger this across a large number of your sends, and you won't see it coming until the bounces start stacking up. You can check your SPF in about 30 seconds with our free SPF checker. If you're stuck on what the bounce message is actually telling you, the SOS hotline is free and we'll help you read it.
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