On Wed, 27 Apr 2005, Scot Jenkins wrote: > On 4/26/05, Jon Schewe <jpschewe at mtu.net> wrote: >> I've setup a machine to be a secondary mailserver and just queue up mail >> until the main mailserver comes back up. I'm using sendmail (no, I can't > > I just googled for "sendmail secondary valid email addresses". This > first hit seemed to indicate what you want to do is possible: > > http://lists.freebsd.org/pipermail/freebsd-isp/2005-February/002796.html I know of a similar setup that doesn't use Milter (if Milter isn't a good optin for Jon), but neither option will work well when the primary is down. The aliases trick should work, but you have to alias the addresses to the 1st box (Jon didn't say what you were doing with aliases), ala: john: john at primary.mx.example.com bob: bob at primary.mx.example.com ... So your backup server would have your domain in local-host-names (which you said you did, and is correct for what you're trying to do), and then an alias entry for every valid recipient, pointing to their username at the 1st box. Just make darn sure you keep the backup system up to date - or you will end up bouncing mail for legitimate recipients when your primary is down. I didn't see any qualification as to how "big" this mail setup is, but if you're managing this for a lot of users, there are some ways to automate something like this. It is extremely dangerous (values for "extremely" vary depending on who and how many you're doing mail for) to have two machines both think they are the final destination for a domain (excepting obvious things like clusters and load balancing...) Just keep in mind what you're exposure is if the backup isn't up to date, or falls over in some extraordinary way.