Well, I'm only in the initial stages of thinking about this, but consider this: Exchange Web Services is SOAP for Exchange 2010.Hey, My ISP/SysAdmin doesn't want me to use POP3/IMAP! I don't want to use Linux and set up another email server and procmail... I just want to get mail from my Exchange Server! Also, I want the email to arrive *faster*!
This idea isn't fully tested or realized, so bear with me if this doesn't make sense.
There's a perl module: Email::Folder::Exchange::EWS that enables you to communicate with EWS in the same manner that your SmartPhone does.
OTRS already has "Generic Interface" ready for SOAP connections, so it would appear that if there were some sort of configuration to make the Generic Interface talk to Exchange Web Services, you could use Exchange Push notification with the OTRS Generic Interface as a Provider (?) to tell OTRS to grab emails.
Basically, I'm thinking of the path like this:
OTRS as a Provider listens for Exchange Push notification, then goes to grab emails and creates tickets (and deletes them as they're downloaded).
Don't ask me how to do it. I am still trying to figure it out myself. I do believe it's possible, however, and probably not as complicated as it may appear.