As said, our client gets regularly spam by a botnet maintainer over your IP systems. We have opened issue
[Online] Abuse #266317
for our client. This botnet sends fraud advertisements or fake subscription spam. We would be happy if it would be possible to exclude the mail of our client from your system - perhaps you can put it on a general blacklist which is forbidden to send to.
Anyway, the constant spam/phishing is highly annoying, and our client - and we - expect that situation to stop.
For any help and contact - which could lead to a solution, we would be thankful.
Team-leader non-profit White-Hat anti-abuse investigations (online) collective