How do Yahoo’s “temporarily deferred” errors behave?

Yahoo's temporarily deferred errors indicate that Yahoo is accepting your connection but delaying message acceptance. These deferrals typically include 4xx error codes with messages like "temporarily deferred" or "try again later." They signal that Yahoo has concerns but has not fully blocked you.

Deferrals often occur during volume spikes, when reputation signals are mixed, or when Yahoo's systems are under load. The appropriate response is to slow down sending and retry with exponential backoff. Most ESPs handle this automatically, queuing messages for later delivery attempts.

Persistent deferrals lasting hours or days suggest deeper reputation issues requiring investigation. Check your authentication, review recent complaint rates, and examine whether content or sending patterns changed recently. Yahoo uses deferrals as a soft enforcement mechanism before moving to hard blocks.