ref: ffec157d3bda49c52a9b832415e2adecde566c06
dir: /popimap.ms/
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