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michalskim
New Member

Mail server throttling issue

Since we moved to Comcast Business internet on 6/24 we have been seeing issues with messages to customers being throttled on a mail server.  These messages must go out in a timley manner because they are letting customers know that items are ready to be picked up at thier local library.

 

Can you white list us or something like that to stop the throttling? 

 

Log message below.  Email user name and IP redacted for privacy reasons.

 

50 *** sendmail[20945]: x6K9QJ70015596: to=<redacted_user@comcast.net>, delay=22:06:30, xdelay=00:00:01, mailer=esmtp, pri=2191366, relay=mx1.comcast.net. [IP Address Redacted], dsn=4.0.0, stat=Deferred: 421 4.1.0 208.89.32.36 Throttled - try again later. Please see http://postmaster.comcast.net/smtp-error-codes.php#RL000003

 

I also saw a similar post in the Xfinity forum.  Not sure if that helps, link here: https://forums.xfinity.com/t5/Email-Web-Browsing/Mail-Server-Throttling-and-Connection-Problems/td-p...

 

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3 REPLIES 3
Official Employee

Re: Mail server throttling issue

Hello michalskim and welcome to the business forums.

 

I can certainly understand your concern as your emails need to be sent in a timely manner. Comcast does not throttle. I appreciate you letting us know of this issue. You may need to implement a reverse DNS if you are subscribed with a static IP. This may be something you may need to verify with your host or IT personnel first before we implement any changes with that. 

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michalskim
New Member

Re: Mail server throttling issue

We had opened a ticket with Comcast Business support over the phone last week, ticket number [redacted customer specific information from public thread].  The tech on the phone said that they do throttle and that over time our server would become more "trusted" and less emails would be throttled.  We explained that this was not exceptable as this is a business and the email messages are time sensitive.  We never got a call back from the support rep although they said that this would be escaleted.  Any advise on how to proceed?

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Official Employee

Re: Mail server throttling issue

That ticket number (which I edited out for you, since it's account specific and this is a public thread) means that this is with our Security team and they would be the only ones that can view it. I would advise you reach out to them at abuse@comcast.net or call at 1-888-565-4329. 

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