Thanks for your reply.
I guess I should have mentioned that they are no longer listed, but they were earlier in the day. Here is a couple of the messages I was getting when my mail bounced.
188.8.131.52 does not like recipient.
Remote host said: 553 Blocked - see
h t t p : / / w w w . s p a m c o p . n e t / b l . s h t m l ? 2 0 9 . 6 8 . 5 . 9
Giving up on 184.108.40.206.
(sorry about the extra spaces above, it won't let me put a link in since I'm a newbie)
220.127.116.11 does not like recipient.
Remote host said: 550 IP 18.104.22.168 found in RBL cache
Giving up on 22.214.171.124.
(126.96.36.199 is the ip address for relay00.pair.com)
It looks like Pair has now had their mailservers removed from any blacklists. My concern is that this may be a common problem. Even though they may stay on top of keeping their servers off of the blacklists when they get listed, it is still very inconvenient to have e-mails getting bounced back and having to re-send.