We have a lot of customers using our system for sending out emails. But all emails to domains of virginmedia.com, ntlworld.com and blueyonder.co.uk are failing.
When our SMTP server connects to your SMTP server for delivering mails, it gets a respons that our IP is blocked. It started blocking on December 14th.
This is the response when I do a manual telnet from our server to your server:
>telnet mx.tb.ukmail.iss.as9143.net 25
421 mx9.tb.ukmail.iss.as9143.net mx9.tb.ukmail.iss.as9143.net MXIN107 Connections from your IP 220.127.116.11 have been disallowed by admin policy. ;id=rgRDkp6irdDru;sid=rgRDkp6irdDru;mta=mx9.tb;d=20201222;t=130647[CET];ipsrc=18.104.22.168;