David Brodbeck wrote:
On Sun, 30 May 2004, Greg Connor wrote:
Seriously, accept-then-bounce is quickly falling out of favor and can
already get you blocked some places. At least you know what you have to
fix next... make it so all your MX servers know the valid *destination*
addresses so that they won't accept mail that can never be delivered.
I would really like to do this, but I'm not sure how to get it to work
in
my situation. Any suggestions would be greatly appreciated. Our MX
host
is a Linux system running Exim. It accepts incoming mail and then sends
it on to Exchange 5.5. You see the problem -- Exim has no ready way of
knowing what is or isn't a valid address when it accepts the mail.
Please don't suggest "get rid of Exchange" because it's not going to
happen. We rely too heavily on the calendar and free/busy scheduling
features. Likewise, getting rid of Exim and exposing Exchange directly
to
the Internet is likely to cause far more problems than it solves.
Option 1:
Live forward. Attempt delivery to the Exchange server before reporting
acceptance back to the originating server.
Won't work with Exchange 5.5 - there's no recipient validation at SMTP
time in that version, it accepts everything in domains it considers
'local'.
Option 2:
Use a directory service. Validate the recipient address through
your internal directory service before accepting it in Exim.
Yep, you can query the Exchange 5.5 GAL from Exim using LDAP. There's a
recipe around somewhere, GIYF.
Option 3:
Write some scripts to regularly export the GAL to a format the Exim box
can grok directly. Might be simpler that 2.
Should we head over to the Exim list for further discussions on this?
Peter