Last Friday, all our mail servers started getting this error when sending to any addresses @att.net, @sbcglobal.net, etc.:
553 5.3.0 flpd576 DNSBL:RBL 521< 208.80.4.152 >_is_blocked.For assistance forward this error to abuse_...@abuse-att.net I've written to the abuse_...@abuse-att.net address twice from different addresses, but received no response (not even an autoresponse) after > 72 hours. The error appears at the MAIL FROM stage, and it doesn't matter what the HELO or MAIL FROM text is. The messages would pass SPF/DKIM/DMARC, although it never gets to the DKIM stage. The blocking is clearly IP based, although it encompasses all of our IP space (four separate /22 netblocks). We're sending from the same IP addresses we've been using for 15 years, with no change in behavior or uptick in complaints, and the servers are not listed on any publicly accessible RBLs that I can find. Are other people seeing anything similar? Does anyone have any tips for solving this, beyond "keep writing to abuse_...@abuse-att.net"? -- Robert L Mathews _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
