Use the newly added mailnull user, and the now well-established group
mail.
The use of compile-time defaults for these values is not required for
many sites, but are important for more exotic applications.
This ensures that the packages are useful to the widest audience
possible.
Bite the bullet _now_ and use MTA user exim instead. This means that
only early adopters of Exim-3.31 are affected, rather than lots more
folks further down the line.
I still think mailnull is better, but nobody in the Exim community
agrees with me. :-)
Bump PORTREVISION as appropriate.
Since BSD UNIX still doesn't offer a user for running an MTA in a
sandbox the way many Linux distributions do, the Exim port uses
the traditional sandbox user for sendmail, called 'sendmail'.
Bump PORTREVISION accordingly.
