I had a debate about alternative platform support with the CCBU for Agent Email. The short answer I got was while there is nothing intentional custom to Exchange that won't make it work, they haven't tested it so you're on your own as far as TAC is concerned. Apparently Cisco policy requires they test with a specific product, not just a protocol/interface - IMAP and SMTP in this case. Since the majority of their customer base uses Exchange they choose to test against that. There was no specific commitment to expand beyond this unless they started hearing noise from the channel.
The way that this functions is to use an IMAP connection to the mailbox. The To or CC fields are matched against configured CSQ email addresses. When a match is found, when an agent takes action on an email, etc CCX moves the email from one folder to another inside the mailbox. The only reason you have to create all of those distribution lists in Exchange is because if you were to assign an alias to the mailbox, it wouldn't actually show as the address in the To or CC field, I guess.
Along the same lines, sending an email is just an SMTP transaction. There is nothing that was intentionally customized for Exchange, it's just what they choose to test against. I would encourage you to configure it with Groupwise anyways and test it thoroughly.
