To offer IMAP with mandatory TLS:

cpu% cp	(/bin/service/)^(!tcp993 tcp993)

#!/bin/rc

exec tlssrv -c	/sys/lib/tls/acmed/example.com.crt  -limap4d
-r`{cat	  $3/remote}   /bin/upas/imap4d	 -p  -d	 example.com
-r`{cat	$3/remote} >>[2]/sys/log/imap4d