SMTP code 421 4.7.0 TSS05
What the knowledge base's own tables say about this code, and which articles say it — a description of the reply, never a placement prediction.
- Provider
- Yahoo
- Response matched (regex, abridged)
- 421 4.7.0 [TSS05] (deferred, user complaints)
- Trigger
- 2/hr
- Action
- Suspend
- Duration
- 4 h
From Per-Provider Tuning Baselines · Automated-throttle rules per provider (community-contributed)