Level: Advanced
Receiving mail servers actively limit how quickly they'll accept messages from a given sender, and understanding this behavior helps distinguish a genuine deliverability problem from expected, temporary throttling.
Throttling Is a Normal, Expected Behavior
Receiving servers commonly limit the rate of incoming connections or messages from a given sending IP, particularly for newer or lower-reputation senders, as a standard protective measure.
Repeated Throttling Responses Aren't Necessarily a Reputation Problem
A temporary rate-limit response during a large send is often simply the receiving server managing its own load, not a sign that your sending reputation has degraded.
Sustained or Worsening Throttling Can Signal a Genuine Issue
If rate limiting persists or intensifies over repeated sends despite otherwise stable sending patterns, it's worth investigating as a potential reputation or configuration problem rather than dismissing it as routine.
Next step: Use the Server Status Checker to check your sending server's current status and recent response patterns to distinguish normal throttling from a genuine issue.