I doubt very much the message class has anything to do with this – other applications such as fax servers and such use their own message classes and if the archiving software can’t handle that, it’s pretty weak.
If I had to guess (and this is just a guess, I’ve never used this package and I know nothing about it) it’s choking on the other extended MAPI attributes we add to the message – it takes more than just an attached WAV file and a message class of IPM.Note.Voice.Unity to flag a message as a voice mail.
This is something you should really bring up with the archiving product company, not us. Unity isn’t doing any illegal or ugly here – if they’re choking on the message, they need to look into why. You can see an example of what we do with a message on the code samples page here:
http://www.ciscounitytools.com/CodeSamples.htm
at the bottom is an example of taking an email and converting it into a voice mail via CDO interfaces – perhaps you can shoot this to them to have a look – they should be able to repro it reasonably easily with that.
