Yahoo TS03: deferred for policy reasons
Yahooreputation_blockaction: pause
Yahoo's [TS03] tag marks a deferral for policy or reputation reasons. It arrives as a 4xx, so the message is still queued, but it is a reputation signal rather than a capacity one. Back off and look at your complaint rate.
A good example of why status-code class alone is a poor guide. This is a 4xx, which normally means retry, but the message text explicitly says retrying will fail. Bounce classification has to read the text.
What it looks like in the log
421 4.7.0 [TS03] All messages from x.x.x.x will be permanently deferred; Retrying will NOT succeed.421 4.7.0 [TSS04] Messages from x.x.x.x temporarily deferred.Why it happens
- Complaint rate above what Yahoo tolerates.
- Spam trap hits on Yahoo-operated domains.
- A volume pattern Yahoo reads as unestablished or abusive.
What to do
- Read the text, not just the code. "Will be permanently deferred; retrying will NOT succeed" means stop, despite the 4xx.
- Enrol in Yahoo's complaint feedback loop and make sure complaints reach suppression.
- Reduce volume to Yahoo domains and rebuild with engaged recipients only.
Related
Warm-up planner builds a ramp that grows at a rate Yahoo will accept rather than one that spikes. Open warm-up planner