Removal of postfix from base

[Mikael Eriksson]

Scott James Remnant wrote:

> I propose we move postfix into supported, where it can live with the
> other servers.  We could consider promoting exim4 into universe in its
> place also, but that's a different argument.
> 
> In base, I suggest we aim for the simplest possible MDA.
> 
>  1) not a daemon, provides only /usr/sbin/sendmail
> 
>  2) delivers mail locally

esmtp-run does this.