Att.net and sbcglobal.net emails undeliverable
Delivery to every recipient with an att.net or sbcglobal.net email address fails with the following message:
host al-ip4-mx-vip1.prodigy.net [22.214.171.124]
SMTP error from remote mail server after MAIL FROM:<[email scrubbed]>:
553 5.3.0 alpd683 DNSBL:RBL 521< 126.96.36.199 >_is_blocked.
I've sent the errors to this email address as instructed: email@example.com. It's been a week now and is impeding our ability to do business, especially as we are all operating remotely at this time.