Unable to Read SMTP Greeting error when sending to Comcast address

Problem:  When my users are trying to send an email to Comcast, aol, q.com, etc.. they would get an error that said: “Unable to deliver message to: <Person@comcast.net> Delivery failed for the following reason: Unable to read SMTP greeting from mx2.comcast.net[68.87.20.5] This has been a permanent failure. No further delivery attempts will be made.” I […]
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