Question : Email routing between MS-Exchange and M-Daemon email server

We want setup email routing between MS Exchange and M-Daemon.Our requirement is as follows.

a)      We will have the Exchange system as it is running now.

b)      We shall build up a second email server within the same domain abcxyz.com

c)       Emails arriving to abcxyz.com (our domain) will be checked by exchange AD if the address is present in its directory else forward it to the M demon server.

Can any one suggest us how will we will design and configure it.

Answer : Email routing between MS-Exchange and M-Daemon email server

Which version of Exchange?

You are sharing the SMTP address space.
Exchange 2003: http://support.microsoft.com/kb/321721
Exchange 2007: http://technet.microsoft.com/en-us/library/bb676395.aspx

Simon.