Due to a knew provider I had to change all of our outside A and reverse lookup records. We can resolve names just fine but not IP's. We have a 24bit mask and I created our records with the last octet of each IP - ie x.x.x.249 has a reverse record of 249. Due to this problem we are having a lot of mail rejected by other institutions. I had one of them do an nslookup to our mail servers IP address for me and the result was - default server unavailable, server failed. Any ideas what might be wrong?

Thanks in advance