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virgil_s's profile

1 Message

Friday, September 8th, 2023 4:41 PM

RBL delisting - definitely a false positive to be corrected

AT&T/Prodigy is blocking our messages (from a large bank)

Unknown address error 553-'5.3.0 alpd683 DNSBL:RBL 521< >_is_blocked.For assistance forward this error to

The IP is not new, it has a very well established reputation, messages are 100% signed and authorized, fully DMARC compliant, no marketing.

The email address listed in the error is unresponsive for weeks now.

Looking for human to discuss.

Community Support


224.9K Messages

3 months ago

We understand the urgency to get your email unblocked,@virgil_s.

Let me get you in the right direction.  Please contact AT&T Postmaster to resolve your E-mail issues.


This site is intended for ISPs, email providers, and other service providers who want information about the AT&T email service, how it works, and how to resolve related issues.


Also, we suggest reaching out to the AT&T Business Forums team. Some email users who were blocked were able to find a resolution after reaching out to them.



If you need help with anything else, just let us know.
Thank you for visiting the AT&T Community Forums.

Irene, AT&T Community Forum Specialist

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