Important: Create and use a login/password to more effectively use SORBS and get more-detailed info. SORBS dings the IP for spam and for spamvertising of URLs. The entries for spamvertising are shown as "Historic (Inactive)". Spam entries (4). The four entries were received on these date: 04:30:02 24 Apr 2021 GMT-04 04:30:01 24 Apr 2021 GMT-04 04:49:44 16 Apr 2021 GMT-04 17:07:50 12 Apr 2021 GMT-04 Claimed spam #2 was asserted to have spamvertised URL "j.mp". (Which doesn't matter, as that's inactive.) Apparently, delisting in this case will require opening a support ticket. Michael, you care to? Likewise, Barracuda Central does, in their case by filling out a Web form. https://www.barracudacentral.org/rbl/removal-request For DNSBL bl-h1.rbl.polspam.pl , I have no idea if there is a delisting method. For Barracuda Central, man, are they ever broken. https://www.barracudacentral.org/reputation?pr=1&ip=96.86.170.229 shows a blank page. The page for the all.s5h.net DNSRBL redirects to http://www.usenix.org.uk/content/rbl.html for removal information. Says you must visit http://www.usenix.org.uk/content/rblremove from the IP of the listed host -- e.g., by doing curl -4 http://www.usenix.org.uk/content/rblremove from the console. There is also a manual removal process, alternatively. dnsbl-1.uceprotect.net , we've already talked about, there being an express removal Web CGI, but with the warning that they consider us to have been guilty within the last 7 days of sending spam to a spamtrap. (We could wait a week, and see if my mass-removal happened to fix that.) black.dnsbl.brukalai.lt apparently uses the UCEPROTECT-Level 1 list, covered above.