Sent Email Bounced

After sending emails to a family member at RCN.COM for over 25 years my emails are now being returned as "could not be delivered".  I can  send email to that address from GMAIL and YAHOO but not from Comcast on my Computer or phone.  I can RECEIVE emails from RCN.COM but cannot send.

Here is the header from a failed email:

------ This is a copy of the headers of the original message. ------

Return-Path: <[Edited: "Personal Information"]>
X-Received-HELO: from [96.103.146.62] (helo=resdmta-a2p-641405.sys.comcast.net)
Authentication-Results: mx01.rcn.email-ash1.sync.lan header.DKIM-Signature=@comcast.net; dkim=pass
Received: from [96.103.146.62] ([96.103.146.62:36214] helo=resdmta-a2p-641405.sys.comcast.net)
 by mx.rcn.com (envelope-from <[Edited: "Personal Information"]>)
 (ecelerity 4.4.1.20033 r(msys-ecelerity:tags/4.4.1.0^0)) with ESMTPS (cipher=DHE-RSA-AES256-GCM-SHA384) 
 id 97/D9-01697-72889C76; Thu, 06 Mar 2025 06:33:59 -0500
Received: from resomta-a2p-647655.sys.comcast.net ([96.103.145.235])
 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 256/256 bits)
 (Client did not present a certificate)
 by resdmta-a2p-641405.sys.comcast.net with ESMTPS
 id q9Btto9D8pb4kq9UFtWI2P; Thu, 06 Mar 2025 11:33:59 +0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net;
 s=20190202a; t=1741260839;
 bh=yBdIv9oRxGQjNnHZuJ32dJgHpIljjZ6HqOv2JhkB9JE=;
 h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version:
  Content-Type:Xfinity-Spam-Result;
 b=vZSL1fKjiacJelf8caBfzAcsKUw/+LkBYZmPE4W7RFxaaHHwg53To39PS3zBBBvQG
  ztKa6CKrhIbRRXFbVrp+2WTYgRw660u/I4NtjZFcDIHxTr/Qxv3hpVned4FVihZxAp
  Pyvzy1J7wufsKs/y5NDjJPPUtLVjnhfD7/B37jA3ZDu94u3XsaxpnUW52x4KCxgyVQ
  T71mIwCjwjqNTcfNVHxsnixL/X5B9HFfmtkLP8dqp3cCa14eDwpGxJtMCt8rACxCf2
  cVLZuALPgOUinvk5yQvyg3oQV/sD48ZRjP+zal6vQYoQLbXn0FdTk5ChLXrl4Tftgm
  m9bL6BjgnOyiQ==
Received: from NucBoxG3 ([146.168.95.142])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 256/256 bits)
 (Client did not present a certificate)
 by resomta-a2p-647655.sys.comcast.net with ESMTPSA
 id q9U7tonNFSIMQq9U8tIYlS; Thu, 06 Mar 2025 11:33:56 +0000
From: <[Edited: "Personal Information"]>
To: "One Way" <[Edited: "Personal Information"]>
Subject: I Need A Router!!!
Date: Thu, 6 Mar 2025 06:33:51 -0500
Message-ID: <000001db8e8b$a594eac0$f0bec040$@comcast.net>
MIME-Version: 1.0
Content-Type: multipart/alternative;
 boundary="----=_NextPart_000_0001_01DB8E61.BCBFCD20"
X-Mailer: Microsoft Outlook 16.0
Thread-Index: AduOi3jUtG/jczCpQG2YIB6oA1x7QA==
Content-Language: en-us
X-CMAE-Envelope: MS4xfDOYOmJb7evzZdxt3kvxj+HHkKql0OuvXEBiVBo19ZapOCW5UQYvM0ET1OTNa7Q6XaRy24f8dZLBEgr27rqY3d7T2oS6HZE1QE7gdQxwB8T+wj+GGaEi
 WBvQ//NCxxRN8pzlL6w9ckodeR8lswF6N0LKCRBb86ku3gz0rPb59XppnkKbAxcvIc9S/IYpXnsgBQ==
X-Vade-Verdict: clean
X-Vade-Analysis-1: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgddutdejieehucetufdoteggodetrfdotffvucfr
X-Vade-Analysis-2: rhhofhhilhgvmecuufgjpfetvefqtfdptfevpfdpgffpggdqtfevpfenuceurghilhhouhhtmecufedt
X-Vade-Analysis-3: udenucenucfjughrpefhvffufffkgggtofhtsegrtdhgpedvtddvnecuhfhrohhmpeeojhhovghpfihp
X-Vade-Analysis-4: sgestghomhgtrghsthdrnhgvtheqnecuggftrfgrthhtvghrnhepudeffeffgeetudeghefhlefgfeef
X-Vade-Analysis-5: keeggfdvgfeijeegfeekheetgeetjeeljeeunecuffhomhgrihhnpehrvghuthgvrhhsrdgtohhmnecu
X-Vade-Analysis-6: kfhppeeliedruddtfedrudegiedriedvpddugeeirdduieekrdelhedrudegvdenucevlhhushhtvghr
X-Vade-Analysis-7: ufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeeliedruddtfedrudegiedriedvpdhhvghloheprhgv
X-Vade-Analysis-8: shgumhhtrgdqrgdvphdqieegudegtdehrdhshihsrdgtohhmtggrshhtrdhnvghtpdhmrghilhhfrhho
X-Vade-Analysis-9: mhepjhhovghpfihpsgestghomhgtrghsthdrnhgvthdprhgtphhtthhopehnfhhpihgriiiisegvrhho
X-Vade-Analysis-10: lhhsrdgtohhmpdhmthgrhhhoshhtpehmgidtuddrrhgtnhdrvghmrghilhdqrghshhdurdhshihntgdr
X-Vade-Analysis-11: lhgrnhdpshhpfheppdgukhhimhepphgrshhspdhnsggprhgtphhtthhopedupdhishgpnhgrpehtrhhu
X-Vade-Analysis-12: vg
X-Vade-Client: EMERALD

I cannot contact Comcast directly because my email address is grandfathered in from a previous account.  Any assistance would be appreciated.

Joe P