Mail from my list server (list.xcski.com, ip 18.104.22.168) to [your customer] is getting bounced with the message:
<[your customer]>: host domain-relay.mspring.net[22.214.171.124] said: 550 Dynamic IPs/open relays blocked. Contact <email@example.com>. (in reply to MAIL FROM command)
And when I try to email the address that it says to contact, I get a further bounce:
<firstname.lastname@example.org>: host madm-corleone.atl.sa.earthlink.net[126.96.36.199] said: 550 Unknown local part openrelay in <email@example.com> (in reply to RCPT TO command)
First of all, I’m not an open relay. Never have been, never will be. And unlike you, when I have an error message say “Contact:”, I make sure the email address actually exists. Can you bozos please fix your open relay check, and fix your bounce messages?