I am in the process of rebuilding one of our relay servers that was recently lost due to a hardware failure. In addition to updating the hardware I am also upgrading the the OS from rhel3 to rhel5. Does anyone know if the sendmail.cf is OS version or sendmail version specific, and if so is it backward compatible?

We, unfortunately, have a very complicated sendmail setup and what I would like to do is to take the sendmail.cf file from the failed server (a copy was saved on nfs) and drop it into /etc/mail/. If it makes a difference I still have the ability to access the one of the drives from the old server and I could grab the entire contents of /etc/mail if there was one or more additional files that were also needed.

Any advice would be greatly appreciated.

I have done this before, and it does work. I don't think it's OS dependent, but it does look at the version of Sendmail, though. HOWEVER

My sendmail.cf files aren't that complicated, and on one 'move', I got a warning about the version of sendmail.cf being older. It still worked, though, but I did wind up upgrading it later, just to be safe.