530 5.1.0 Sender Rejected for all emails sent to Comcast.net customers

Hello, I'm having the same issue and am seeing "530 5.1.0 sender rejected" on all my emails sent to Comcast mailboxes. I'm not able to see where this chat button is to send a DM though. Are you able to help resolve the issue? Thanks!

Greetings, @user_6z6s8b! I hope your week has been treating you well. Thanks so much for taking a moment out of your busy day to leave a post on our community forum. I'm sorry to hear you're having issues sending messages to Comcast email addresses, but you have definitely come to the right place for assistance.

Have you already tried contacting the Comcast Postmaster at https://postmaster.comcast.net/block-removal-request.html to see if your IP address was being blocked by our filters?

@XfinityJamesC​ Hi, thanks for the reply. The IP shouldn't be blocked. My understanding is that it's blocking based on the TLD, as I tried sending email from 2 domains, a more professional one from .tokyo which was received, and a more private domain from .pw, which was blocked. But that seems like a silly way to filter email, because there's nothing inherently bad about .pw, other than it's lesser known. My own Comcast mailbox is filled to the brim with hundreds of spam emails coming from popular TLDs like .com, .org that Comcast's filters completely fail to pick up on. It's quite frustrating.

Edit: To corroborate this, in my own email filters, I can see that .pw is listed as a "fishy tld" by the default lists, however this only applies a tiny hit to the spam score, so the email is still considered good and is received.

We can understand the frustration, and we do have the process to submit and unblock sites.  You can also use this site to request that unblock. 

That linked page only talks about unblocking IPs though, and the request form asks for a list of blocked IPs, but the IPs are not blocked for me. I will try submitting a request anyways though.