Empty $reply_to address invokes validation exceptions.

Fixes password sending. Thanks, saccade.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5749 2fea6a4d-a838-0410-917b-93a53c48e9d2
Correct variable name.

git-svn-id: http://textpattern.googlecode.com/svn/development/4.x@5750 2fea6a4d-a838-0410-917b-93a53c48e9d2