Thanks for the info Ray.
From my experience with Bounce Managers, it isnt' really that difficult in how it functions - and should work with any SMTP server.
1: All returned messages will land in a specific mailbox. These will be errors from the originating SMTP server (ie: could not find MX records), a return from the receiving SMTP server (ie: mailbox does not exist), or even an automated message from the recipient (ie: vacation responder).
2: A Bounce manager simply collects all these returns (either as a scheduled task, or run manually) and analyzes each return.
3: What it analyzes each message against is the key to it's success. One system I've been using is actually using an XML file. Each phrase on the file is given a numerical value.
eg: "mailbox does not exist" = 5, "user not found" = 5, "mailbox is full" = 3, "vacation" = 1, etc... etc.... This type of system makes it really easy to update manually since it is just a text file.
4: After the Bounce Manager retrieves a value - it updates the email address record by increasing certain values in the database. A value of 5 will increase the HARD BOUNCE by 1, while a value of 3 would increase a SOFT BOUNCE by 1. Vacation responders are simply ignored.
In the end you can decide how you want to deal with these "counts" outlined in #4. At the very least, you should not be sending emails to anyone that has Hard Bounces.
Sorry for the long post. Since you said you would have to figure out a way to do it - I figured I would provide 1 possible solution to look into.