I think it will be something along the lines of there are no stats for counting it so that would have to be added first to create something to limit against.

There could be multiple domains in a single server so presumably it would be easily dodged or difficult to track if the same domain is added to multiple servers.

Hi Jan,

there is usually no hard technical reason. It is mostly a complexity and product-scope issue.

Per-server limits are easy because Postal controls one server queue. Per-recipient-domain limits require tracking separate counters and schedules for many domains at once, plus handling retries and multi-recipient messages. That makes queueing and delivery logic much more complex.

So it is likely not impossible, just significantly more complicated than server-level throttling.