# cd /var/qmail/supervise && qmailctl stop 
# install -d -m1751 vpopmaild && chmod 1700  vpopmaild && chown qmaill:qmail vpopmaild && install -d -m751 vpopmaild/log && chmod 0700  vpopmaild/log

# printf '%s\n' \
'#!/bin/sh' \
'QMAILDUID=`id -u vpopmail`' \
'NOFILESGID=`id -g vpopmail`' \
'VPOPD=/home/vpopmail/bin/vpopmaild' \
'' \
'exec 2>&1' 'exec /usr/bin/tcpserver -vRHD -u "$QMAILDUID" -g "$NOFILESGID" 127.0.0.1 89 $VPOPD' \
>./vpopmaild/run

# printf '%s\n' \
'#!/bin/sh' \
'LOGSIZE=`cat /var/qmail/control/logsize`' \
'LOGCOUNT=`cat /var/qmail/control/logcount`' \
'exec /usr/bin/setuidgid qmaill \' \
'     /usr/bin/multilog t s$LOGSIZE n$LOGCOUNT \' \
'     /var/log/qmail/vpopmaild 2>&1' \
> ./vpopmaild/log/run

# chown -R qmaill:qmail vpopmaild && chmod 0751 ./vpopmaild/run && chmod 0751 ./vpopmaild/log/run
# qmailctl start && firewall-cmd --zone=public --add-port=89/tcp --permanent && firewall-cmd --reload

# telnet 127.0.0.1 89
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
+OK
quit
+OK
Connection closed by foreign host.

vpopmail daemon documentation