Hello Johann,
> * Would it be possible to configure exim to generate a key for a
> user on the fly and store it in the database if the user does not
> have already one?
You might be able to do this in one of DATA acls with "warn" acl (that
does nothing for ACL, but might run some command you want executed at
that point).
Alternativaly, in a simpler setup, you might add this function in a
transport_filter script in transport.
Regards,
Marcin Krol