Is there a recent change to comcast SMTP service?
I'm the moderator of an academic mailing list. I've written a program to distributed approved emails to the appropriate listserv. Since I have comcast for internet, I send them out via smtp.comcast.net port 587 using TLS. This has worked without problem for the last number of years. However, starting last week (it might have been a little earlier than that, but the mailing list has fairly low volume) emails that I send seem to fall into a black hole. I did some debugging, and the dialog from the comcast SMTP server indicates that the email was accepted. I even tried to have it (as a test) sent to my work id instead of the listserv. It never appeared. So is comcast blocking such?