FM / pid

/var/spool/postfix/pid

Name	Size	Mode	Actions
inet.127.0.0.1:12346	0	0600	edit dl rm
inet.smtp	0	0600	edit dl rm
inet.smtps	0	0600	edit dl rm
master.pid	33	0600	edit dl rm
unix.bounce	0	0600	edit dl rm
unix.cleanup	0	0600	edit dl rm
unix.defer	0	0600	edit dl rm
unix.error	0	0600	edit dl rm
unix.plesk-89.39.7.190-	0	0600	edit dl rm
unix.retry	0	0600	edit dl rm
unix.showq	0	0600	edit dl rm
unix.smtp	0	0600	edit dl rm

Edit: /var/spool/postfix/pid/unix.plesk-89.39.7.190- (0B)