Hi
> Server A is a fromt end spam filtering server running Exim. Lowest MX
records point to Server A. Server A filters spam and viruses and forwards
email to server B where the real email accounts are.
First, if you want all your mail going through that spam filter, remove make
that Server A the ONLY mx entry!
> So - if servers in the outside world want to verify an email address - how
would that work? Can exim accept a verify on Server B and pass the request
to Server A ? How does that work and how do you set it up?
There are two ways.
First, use a cron job to copy your user table from server B to server A. So
server A can easily check incoming addresses.
Second, use call-out verification from server A for each incoming address to
server B. This will reflect changes in B's users table more recently, but
will put additional burdon on that Server.
Regards,
Steffen