I have MSP version 9.0 Build 9009. I've read through several forum posts and read several documents but I don't see a scenario like mine.  Everything I see is for multiple clients each sending to an alias of the fetching mailbox.  Here is my scenario:

I have my incoming mail server mailbox set to servicedeskmsp@mycompany.com.

I have clients ClientA, ClientB.  I've set aliases in my incoming mail server such as: ClientAsupport@mycompany.com, ClientBsupport@mycompany.com.  These are both aliases for servicedeskmsp@mycompany.com.  I think I understand how things would work if I could convince the clients to send to their respective aliases...

However, each client has the requirement to continue to send to their own internal email address such as: helpdesk@clientA.com or helpdesk@clientB.com

What is the best way to fulfill the client's requirement and also have incoming requests assigned to the correct account and have notifications work correctly?