Qpopper's configure script tries to detect sendmail in a number of common
paths, but the first guess will always fail, because sbindir contains an
embedded shell variable.

As a result, systems without base sendmail (more specifically, without
/usr/sbin/sendmail) will fail configure step.

Additional info:
http://lists.freebsd.org/pipermail/freebsd-ports/2012-March/073828.html

PR: ports/166108
Submitted by: Mel Flynn <rflynn@acsalaska.net>
Approved by: maintainer timeout (14+ days)