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:
$ sudo cat /run/sendmail.pid
/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.