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Blocked Domain, Email or IP address Questions and Discussion


Blocked Domain, Email or IP address Questions and Discussion

Hi, I'm the syadmin of an ESP.   For some reason most of our users with ATT email addresses are unable to receive emails from the system.  We've tried numerous times reporting the issue to ATT blocks, however the issue still exists and our users are getting frustrated.  Can you help please?   


This is the ATT error message from our email server.  We use Elastic Email as our Email service provider.  They believe you are blocking our domain for some reason, as they have already moved us to another ip. 



Here's an example of the error we are getting:


553 5.3.0 alph154 DNSBL:RBL 521< >_is_blocked.For information send an email to abuse_rbl@abuse-att.net


This affects most of the IPs in our netblock ( but not all.  



We've reported this many times now and gotten no reply. It's been over a month.  We've gone through every remediation step listed here:




Filled out the form here a number of times:




We emailed:




I tried this form as well:




Any help would be much appreciated!





Tags (2)
Message 335 of 1,367

Emails Blocked



Emails from our IP sent to sbcglobal.net  and att.net are blocked.

We only send emails to our subscribers from our product web app never spam. Our IP is not blacklisted on any other provider either.

This is creating a huge problem for our members.

How can we resolve this issue?



Message 1201 of 1,367


How do i do a Blacklist removal request


Message 1202 of 1,367


I'm 13 days since my request now and and still no response.

Message 1203 of 1,367

Black list removal request


I’m a system engineer for KUHN Group company

 It seems our mail servers have been blocked by your systems. Please find attached a proof of no-delivery from our cisco appliance.

 We have two public IP which need to be white listed:




Please do it asap as we are unable to send mail to dealers , which impact tour business in USA.

Message 1204 of 1,367

Re: Please remove our IP from your blacklist



We are getting blacklisted by your domain as well.  We have contacted your abuse email but til this day no response.  Can you please tell me how I would proceed to get it removed?


Action: failed

Status: 5.3.0

Diagnostic-Code: smtp;553 5.3.0 alpd681 DNSBL:ATTRBL 521< >_is_blocked.For assistance forward this email to abuse_rbl@abuse-att.net





Message 1205 of 1,367

Re: Please remove our IP from your blacklist

I did finally receive a response today from postmaster support telling me my issue was resolved.  I tested and confirmed we are still being blocked and have replied to update the case.

Message 1206 of 1,367

Re: Please remove our IP from your blacklist

?It will take 24-48 hours before you can email again. i think it took a little over 24 for us.

Message 1207 of 1,367

Re: Emails Blocked

Hello @Logismico,

I am sorry to hear of the issues with the email being blocked! I would be more than happy to provide some additional assistance!

Due to the account specific nature of the concern, I would like to speak with you in a secure setting to gather more details, and determine what steps need to be taken to get this resolved. You will be able to retrieve a message from your Forum’s Inbox where we can connect further.

Talk to you soon! Have a great day!

Nicole, AT&T Community Specialist

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Ask a question to get help from the AT&T Community or support from AT&T specialists. If this reply helped you please use Accept solution to mark it as an Accepted Solution.
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Message 1208 of 1,367

Re: Emails Blocked

I am the IT Manager of a small business. Attempts to send email to customers with att.net and scbglobal.net are blocked with the following bounce messages:
<xxxxxxxxxx@att.net>    (reason: 553 5.3.0 alph131 DNSBL:ATTRBL 521< xxx.xxx.xxx.xxx >_is_blocked.For assistance forward this email to abuse_rbl@abuse-att.net)
<xxx.xxxxxx@sbcglobal.net>    (reason: 553 5.3.0 alph131 DNSBL:ATTRBL 521< xxx.xxx.xxx.xxx >_is_blocked.For assistance forward this email to abuse_rbl@abuse-att.net)

(Email and IP addresses blanked out for security.)

Our mail server IP is not listed on any DNS RBL and has valid PTR and SPF records.
We have sent numerous whitelist requests to abuse_rbl@abuse-att.net, but like so many others, have never received a reply, nor resolution.

We would greatly appreciate assistance in this matter as this is becoming detrimental to our company.

Thank you for your help.

Message 1209 of 1,367

Re: RBL removal request

If you are going to do this kind of thing (not sure what your algorithm is, MXTOOLBOX comes up clean) and provide an email address to report to- you should at least be responsive (not just an auto response) to requests to clear.


al-ip4-mx-vip2.prodigy.net #<al-ip4-mx-vip2.prodigy.net #5.3.0 smtp; 553 5.3.0 alph159 DNSBL:ATTRBL 521< >_is_blocked.For assistance forward this email to abuse_rbl@abuse-att.net> #SMTP#

Message 1210 of 1,367

Re: DNSBL:ATTRBL 521 need help removing from ATT blacklisting

Hello ATT,


We seem to have the same issue, we are not listed on any blacklist and https://www.talosintelligence.com/ has our IP at score of "Good" 

We can send email to everyone but ATT users.

Our IT have already sent 3 emails to abuse_rbl@abuse-att.net but we have no results.


Can someone help us?

Message 1211 of 1,367

Re: Re: Blacklist removal

I have the same problem.   Here is our server IP address: and  Can someone look them up and let me know if they are on the blacklist?   Thank you.

Message 1212 of 1,367

My emails are blocked to domain sbcglobal.net

Here are mail logs: My network is

2018-03-08 17:19:51 1eu4pB-000104-JO <= info@misxxxxxxxxxxx.com H=232.sub-174-235-17.myvzw.com ([]) []:11547 P=esmtpsa X=TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256 CV=no A=dovecot_plain:info@misxxxxxxxxxxx.com S=11110 id=1F024BA7-920C-4555-95C0-9CBD8CC33DEC@misxxxxxxxxxxx.com T="Re: Estimate Query Received" for tinxxxxxxxx@sbcglobal.net
2018-03-08 17:19:51 1eu4pB-000104-JO Sender identification U=mistervalet D=misxxxxxxxxxxx.com S=info@misxxxxxxxxxxx.com
2018-03-08 17:19:51 1eu4pB-000104-JO SMTP connection outbound 1520551191 1eu4pB-000104-JO misxxxxxxxxxxx.com tinalahrmann@sbcglobal.net
2018-03-08 17:19:51 1eu4pB-000104-JO ** tinxxxxxxxx@sbcglobal.net R=dkim_lookuphost T=dkim_remote_smtp H=ff-ip4-mx-vip2.prodigy.net []: SMTP error from remote mail server after MAIL FROM:<info@misxxxxxxxxxxx.com>: 553 5.3.0 flpd592 DNSBL:RBL 521< >_is_blocked.For assistance forward this email to abuse_rbl@abuse-att.net
2018-03-08 17:19:51 1eu4pB-000104-JO Completed

Message 1213 of 1,367

Re: My emails are blocked to domain sbcglobal.net

Hey @ATTCares


Day 15 for me, still with no resolution.  My issue was reported resolved early Tuesday morning by Postmaster.  I've confirmed by testing again this morning that I am still blocked.

Message 1214 of 1,367

Re: My emails are blocked to domain sbcglobal.net

I have done some checking. I did hear back and the IP number is not blocked.
My site works with Comcast and Verizon, but not with AT&T

Message 1215 of 1,367
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