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Mon, Jan 28, 2019 3:01 PM

Blocked DNS - Email

5.3.0 flpd591 DNSBL:rbl 521


The above is the error we receive at a clients location.


Any clear insight would be great to get this resolved.


Accepted Solution

Official Solution

Brand User

Community Support


136.7K Messages

2 years ago

Hello @timthuston,


Thanks for reaching out on the forums, we're here to help! To get started can you confirm if this is a residential account or a business account? Additionally, have you already sent an email to, if not you can check out our Postmaster site for more information. We look forward to hearing back from you!


James C., AT&T Community Specialist

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