[n5bb]

I see various dangerous things in your outgoing message:

• The message was sent through Comcast outgoing servers, so you need to play by their rules to reduce outgoing spam. Residential phone/cable email providers are very worried about spam being sent through their systems (for good reasons).
• You are sending with a non-Comcast From address through their outgoing SMTP server. This might be the cause of the error.
• When I check your From address domain, I find using the free http://http://www.dnsstuff.com tools:

  Malformed greeting or no A records found matching banner text for following servers, and banner is not an address literal. RFC5321 requires one or the other (should not be a CNAME). If this is not set correctly, some mail platforms will reject or delay mail from you, and can cause hard to diagnose issues with deliverability. Mailserver details:
  
  72.167.238.32 | WARNING: The hostname in the SMTP greeting does not match the reverse DNS (PTR) record for your mail server. This probably won't cause any harm, but may be a technical violation of RFC5321
  72.167.238.29 | WARNING: The hostname in the SMTP greeting does not match the reverse DNS (PTR) record for your mail server. This probably won't cause any harm, but may be a technical violation of RFC5321

• Also, you have a Message-Id which looks like a home email server rather than a normal domain name. "@precision-m4600" looks like a Dell PC to me.
• Do you have access to Comcast webmail? If so, then please try sending to that same destination address with your Comcast email address in From using Comcast webmail.
  • If that doesn't work, something must be bothering Comcast about your destination domain. It may be something they didn't like in the past, and you may be on a block list at Comcast. Their support should be able to check this.
• You can also try changing the From address in your email client to your Comcast address and see what happens. I don't know why the Message-Id looks odd, but it might bother Comcast.
• Your destination email address domain (and full published DNS records) look fine to me. I think that Comcast support hasn't really tried sending a message through their server to your domain. They need to actually send a message and look at their server logs. It is very strange that the DSN message says "Diagnostic-Code: smtp;", but there is no actual code. This looks like an abnormal block in their system to me, not a normal SMTP error.
• I hope that others with experience will add their comments here. It may take a couple of days for more people to notice this thread, since this subforum isn't as busy as some others.

Bill