I'd like to propose a generic mechanism for replacing sendmail.  It
provides a method for pkgs of other mailers to replace the in-tree
sendmail in a clean manner.  This is really independent of the sendmail
8.9.0 issues, and would apply even if 8.9.0 is comitted, as there are
still other mailers that may wish to replace at least parts of the
shipped sendmail (namely /usr/sbin/sendmail, for compatibility reasons).

Proposal:

- Create a pkg called "replace-sendmail":
	- On install, renames all installed sendmail files to
	  nonconflicting names or locations
	- On pkg_delete, renames them back.
	- Pkgs of sendmail 8.9.0, qmail, or whatever can DEPENDS+=
	  on replace-sendmail.

- Modify the in-tree sendmail Makefiles to detect if replace-sendmail is
  installed (most likely indirectly, by checking for the renamed files)
  and install in the above renamed or moved locations if so. This allows
  someone with a replacement mailer to "make build" without fear of
  trashing that mailer.

- At least until/if the 8.9.0 issues are involved, create a 8.9.0 package
  that depends on relace-sendmail and installs exactly where 8.8.8
  currently installs

If this is considered reasonable, I'm quite willing to work on it.