I have situation where a client wants to pass emails we send on to their employees, but their Exchange system is locked down such that most employees are unable to receive messages from outside their organization. They are apparently unable to have a whitelist with our sender address (I'm not familiar with Exchange admin so I don't know why that isn't an option). They also do not have a publicly available SMTP server that we could use to authenticate and send from their own system, or at least say they don't.
So the next option we're entertaining is sending our messages all to a single address on their system, with an email address embedded in the subject. Then they would like some sort of rule that would parse the subject for the embedded address and then redirect/forward the original message to that address.
Is there any way to do something like this from the Exchange side? Custom macro filter rules or something? Alternatively, if not that is there a way to do it from the Outlook side?
I don't know the version of Exchange yet, but will edit once I find out. But at this point I'm just trying to figure out what it is that I'm looking for in the first place or what options might be available to implement such a thing.
edit: I've been told this is Exchange 2003. I also did come across something about 'Transport Rules' which sounds like it might be what I'm looking for?