On Sat, 2011-02-26 at 12:08 +0000, Chris Wilson wrote: > Option 3) have the secondary only accept mail when the primary is down > (possibly combined with 2): > http://blog.aptivate.org/2009/01/28/backup-mail-exchangers/
While that's perfectly valid, there are any number of reasons why a given source address would be able to connect to your secondary MX but not the primary. Almost none of those reasons are under your control, nor that of the source. If you're running a high-volume system (in terms of rate, or end users) then this will turn round and bite at some point. As Jeremy mentioned, good practice is to ensure both primary and secondary (tertiary, etc) MX hosts for a given domain have the same "knowledge" of the domain's recipients. There are hundreds of ways to achieve that, aside from doing call-forward verification. Graeme -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
