this is obviously a setting within Gmail Absolutely. The thresholds are even stricter in Yahoo. In my former life I had to set per-domain rate limits in all

this is obviously a setting within Gmail Absolutely. The thresholds are even stricter in Yahoo. In my former life I had to set per-domain rate limits in all the mail servers in all our datacenters or customers could not receive emails. The only other option would have been to relay to email campaign providers which do the same thing I mentioned above however our customer contracts prevented using third parties.