Abdul,

The current version of Xeams does not throttle outbound emails. I can certainly add this in our wish list for a future version.

However, a more important question is why are so many messages going out to Yahoo? Is one or more of your user trying to send out marketing emails? You should be able to search yahoo in message repository to see why are so many messages going out and who is sending them.

Please note that even when throttling is enabled, you will have to figure out who and why are so many emails going out to Yahoo. I say that because once throttling is enabled, it will penalize legitimate emails and they will get delayed.