Sending host is in a blacklist

[ihmedia]

HI

A client of ours is trying to send email through our smtp server.

They get an alert box saying the sendign host 81.152.225.29 is in a black list?

Can someone explain why they are getting this error?

[chirpy]

Search the mail logs in (Linux) /var/log/messages. They may shed some light onto which list is blocking the senders IP address. Alternatively, check on one of the RBL aggregation sites for their sending IP address, such as:
http://www.dnsbl.info/

[ihmedia]

its listed at dnsbl.njabl.org

Someone said its because they send through a dynamic ip?

What can i do, should i leave the setup and just tell them to use there isp's smtp server?

[chirpy]

Yup, that's usually the best idea.