Added a manpage for sendmail(8)

Conflicts:
	mk/smtpctl/Makefile.am
reword
sticky bit on homedir disables .forward lookup like with qmail

suggested by "zx2c4"
missing from previous commit
missing macro .Os caused bogus output
Merge remote-tracking branch 'upstream/master' into dsn
better log SSL certificate checking
fix log message + enable verify in headers
Merge remote-tracking branch 'upstream/master' into dsn
even if OpenSMTPD tolerates a space between a SMTP command and its
parameter, we shouldn't use it in our enqueuer as people could use
our code elsewhere.

diff from Eric Radman
- sync man page with OpenBSD
- rename /etc/mailname -> /etc/mail/mailname
make enqueuer mailname-aware

diff from Ryan Kavanagh <rak@debian.org>
don't abort on an empty static aliases file

diff by Ryan Kavanagh <rak@debian.org>
fix issue #289, we should accept: RCPT TO:<postmaster>
erf, when using fseek() in smtpctl show XXX, do not swap the last
two parameters as this won't work too good.

while at it, lseek() the underlying descriptor before the final
gzcat/cat otherwise things may not work too good
Always set the listener helo, using the local server name by default.
Read this name earlier since it's referenced during config parsing.
Simplify (and fix for missing params in host_dns) listener setup.
In SMTP session, use the "helo" name as domain instead of sc_hostname
for mails sent to <postmaster>.
Simplify code by a great deal (and fix "schedule all") by adding a
generic function for sending a control message to a set of envelopes.
As a bonus, we now report the number of affected envelopes.
fix previous
When a ctl op on an envelope is issued, let the scheduler report the
success or failure and forward it to the client, instead of sending an
ok immediatly.
Move ext from mta_session to mta_envelope to let queue know that
mail has been relayed to a esmtp dsn capable server.