On Wed, Mar 01, 2006, Chris wrote: > I want to set up a backup mx server to field incoming mail when my > primary mail server goes down. I understand how to do this from a DNS > standpoint, but what I don't know is what should be in my > sendmail.mc/sendmail.cf file for this.
> Is there anything special I need to do for this? Anyone know any good > documentation? You need to allow relaying to the main server, see cf/README. PS: from the sendmail X README: Note about Backup MX Servers It is not a good idea to run a backup MX server B for a host A that has stronger anti-spam measures; if mails are sent to A via B, then B may accept them for delivery, but A may reject them and hence B has to sent bounces, which, in case of spam, are most likely to forged addresses, hence those bounces will only cause additional problems. The opposite case (B has stronger anti-spam measures than A) can cause the rejection of mail that A actually wanted to receive. Hence B and A should have the same anti-spam measures; i.e., a system that acts as backup MX server for another one should perform the same anti-spam checks as the main MX server(s).
