Hello, I am a postmaster for a high volume sending domain. We're receiving thousands "delivery temporarily suspended" messages for the majority of our send attempts and have a growing deferral queue for comcast.net recipients. Can you help us figure out why this is happening so we can start sending mail at regular rates again? We filled out the blocklist form, but it indicated none of our IPs are on a blocklist (and we don't see any BL codes in our logs). This is a production impacting situation for our comcast.net recipients, I can provide information on our domain and IP reputation, sending practices, etc if you need it.
@ComcastSPAAbuse our thousands of deferrals all eventually got sent overnight, from around 8:30-10pm MT last night, and are starting to back up again today. I spoke with the CSA department on the phone and they were having trouble actually finding record of our dropped messages, we ran a test from our servers to my personal comcast account and could not get messages through and they weren't finding record of the attempts, even though we were recieving lost connection and delivery temporarily suspended message from your servers. We have been doing some testing and are seeing a very high percentage of dropped connections to your mx servers even when we manually connect from a variety of sources (not just our mail servers).
We're not having problems with any other domains. Can someone help me figure out why we're dropping connections so frequently during (I'm assuming) high volume times?
I am replying to your previous PM with more info.