Description of Problem:
The spec file has the comment:
# No I'm not kidding
above the line:
I just modified the spec to not require sendmail and it built fine with exim,
so I don't see how sendmail can be a build pre-requisite.
Maybe it should require "mailerdaemon" or "/usr/lib/sendmail".
the build looks for sendmail by name.
If you want, you can have a package which /provides/ sendmail, but I feel safer
with this requirement.