This is not a Sendmail question, it is a Linux mail server question.
I work at a little ISP, at present we have two servers, both working well:
1. RH 8 + Postfix + MySQL + Courier-imap + sqwebmail + Bind
2. RH 8 + Apache + PHP 4.3.0 + Bind
and DNS is setup like this
MX 10 server1
MX 100 server2
In server #2 there is no mail server program yet.
I've tried to use PHP's "mail" function in server2 but as I have no SMTP server it didn't work.
So I wanted to install some kind of mail server, and use it also as a secondary server if server1 fails. My aim is that no mail get lost.
Can I setup Postfix as a "catchall" server? (so if server1 fails server2 gets every mail and then when server1 is fixed I guess I can deliver mail back with fetchmail)
Or should I duplicate server 1 maildir and database structure?
Is there a simpler solution?