Can't get exim to work

[Jesper Holmberg <Jesper.HOLMBERG@enst-bretagne.fr>]

When I try to use fetchmail on my newly installed testing/unstable
system, with an .fetchmailrc I've used before on another system, I get
these errors:

reading message 2 of 367 (2998 octets) .fetchmail: SMTP connect to
localhost failed
fetchmail: can't raise the listener; falling back to $sendmail %T.sh:
jesper: command not found
fetchmail: MDA exited abnormally or returned nonzero status
 not flushed
reading message 3 of 367 (2191 octets) ..sh: jesper: command not found

etc...

I expect this to be a problem with my exim, that I've tried to
configure, but I don't know what to look for. It seems to me exim is not
listening to the network.

Any help greatly appreciated

Jesper