[Exim] exim with maildir and courier.sourceforge.net

I am trying to get exim running under debain potato .

then standard configuration works fine for local mail; however the
following is desired:
- fetchmail pulling down email and passing it to exim
- exim putting email into Maildir folders
- courier servering mail via imap from maildir folders - this is done

- it is also desired to not required a unix account to handle mail for any
particular id.

- any input is appreciated - I do not have to have the configuration
described : Just the functionality

Thank you!