Gmail Emails to Multiple Comcast Addresses Rejected – 552 5.2.0 Prohibited by Policy

I'm having a recurring email delivery problem with my Gmail account.

Until recently, I had no trouble sending emails to Comcast recipients. Suddenly, emails from this account started being rejected by Comcast, and the problem has continued.

Here is what I've established:

• Emails from my Gmail account to non-Comcast addresses are delivered successfully.
• Emails to at least five different Comcast recipients have been rejected.
• I've tried sending simple, plain-text emails with no attachments, links, images, or signature.
• The rejection occurs even with a new subject line and a very short message.
• The error returned is 552 5.2.0 [reference code] Prohibited by policy.
• The receiving server identified in the bounce messages is mx2.mxge.comcast.net.
• Most importantly: I sent the exact same message from a completely different Gmail account to the same Comcast recipient, and it was successfully delivered.

This last test makes me wonder whether my established Gmail account or its associated sending reputation is being flagged by Comcast.

My questions:

1. Is Comcast filtering or blocking my specific Gmail sender address?
2. Could my Gmail account's sending reputation or Google's outgoing mail server IP be triggering this rejection?
3. Can Comcast's technical team investigate the rejection reference codes and identify the actual reason for the 552 5.2.0 errors?
4. What is the process for getting this issue reviewed and corrected?

I have several bounce messages with timestamps and rejection reference codes available.

I would appreciate help from someone familiar with Comcast's email filtering or Postmaster team. Thank you!