Mail to Comcast delayed and failing

This just started happening a week ago. Exchange 2019 behind Comcast modem. Error is:

Server at comcast.net (2001:558:fd00:4f::4) returned '400 4.4.7 Message delayed'
12/20/2023 2:39:47 AM - Server at comcast.net (2001:558:fd00:4f::4) returned '451 4.4.397 Error communicating with target host. -> 421 4.2.1 Unable to connect -> SocketError: Failed to connect. Winsock error code: 10051, Win32 error code: 10051'

Original message headers:

Received: from XXXXXXXX (192.XXX.XXX.XXX) by XXXXX (192.XXXXXX)with Microsoft SMTP Server (version=TLS1_2,cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Tue, 19 Dec2023 17:45:28 -0500

Responses

Comcast_ThomasE

Official Employee

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27 Messages

11 months ago

Hello workpc

Have you attempted to reboot your PC? Thank you.

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workpc

New Member

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7 Messages

@Comcast_ThomasE Yes, the Exchange server has be rebooted twice.

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11 months ago

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Comcast_ThomasE

Official Employee

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27 Messages

Are you sending these messages with large numbers of recipients (more than 25) as mass marketing? Typically, delays of the described nature are related those style of large outbound blasts.

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11 months ago

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workpc

New Member

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7 Messages

@Comcast_ThomasE No, these are single messages. I have just 8 sitting in the queue at the moment.

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11 months ago

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Comcast_ThomasE

Official Employee

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27 Messages

Hmmm, that is super strange. Could you please send our team a direct message with your full name and full address? Our team can most definitely take a further look at this issue.

To send a Direct message:
Click "Sign In" if necessary
• Click the "Direct Message" icon
• Click the "New message" (pencil and paper) icon
• Type "Xfinity Support" in the "To:" line and select "Xfinity Support" from the drop-down list which appears. The "Xfinity Support" graphic replaces the "To:" line
https://www.xfinity.com/support/articles/setting-up-auto-paym

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11 months ago

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workpc

New Member

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7 Messages

@Comcast_ThomasE Xfinity Support is not an option, but I can direct message "Comcast Business" like I have in the past.

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11 months ago

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Comcast_JustinC

Official Employee

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26 Messages

11 months ago

@workpc thank you for sending the direct message, I'll follow up with you there to continue.

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