systemd/sendmail problem - seeking help!

[Timothy Murphy]

I'm running Fedora-24(beta)/KDE,
and sendmail/email (through KMail) is failing.
When I try to send email I get the warning "Failed to transmit message",
and journalctl has the entry 
"sendmail.service: PID file /run/sendmail.pid not readable (yet?) 
  after start:  No such file or directory".

I've checked, and sendmail.pid is in place: 
==================
[tim@william ~]$ sudo cat /run/sendmail.pid 
2829 
/usr/sbin/sendmail -bd -q1h 
==================

Googling for the journalctl entry,
I see people have been encountering this problem for years.
But I haven't seen any solution offered.
Several of the comments suggest that it is a systemd problem.

If anyone can offer advice, or even elucidation, I should be most grateful.