I have a domain like mail.domain.com. The site on this domain is runnig on another server and the mailing is on some other. I had made the entries in the DNS for the site and as well as the mail.domain.com. in the mailing server.

The problem, that after a durations of 6-7 hours the entry of the domain.com get's erased automatically from the /etc/localdomains file which results in bouncing mails for that domain. The MX records for the site are running on the mailing server as well as i had made a A record for the mail.domain.com on the same server.

Please any one can help me on this.