Sorry, couldn't grok this last past. Isn't MS exchange IMAP4 IMAP? And why would you want to allow the client to login with a master user? Anyway, you can put "loginuser*masteruser" and "masterpassword" on the username and password boxes on the client as explained by the documentation.
I might not have asked that last question in the clearest way.
The telephone systems access MS Exchange and Lotus notes using the IMAP4 interface of Exchange/Notes and a single (presumably master) username and password. The telephone systems then adds voicemail messages (as a WAV attachment to an ordinary message) to the users inbox and, if the user dials in for their voicemail, they can access the INBOX to find the voicemail messages and play those back. From the users perspective they can either get their voicemail by dialing in, or by reading their inbox and playing the WAV files.
I was wondering whether anyone had any documentation on the differences between using Dovecot with a master user and using exchange/notes with a master user. In other words if the telephone exchange says it fully support Exchange/Notes how much work should I expect in getting it to work with dovecot?
Jon.