If the vm-pop3d daemon is not acting correctly and you are not able to consistently make a connection to 110, you might want to try running it through xinetd.
1) turn of DA checking for the program:
/usr/local/directadmin/data/admin/services.status
set: vm-pop3d=OFF
2) turn off the boot script:
chkconfig vm-pop3d off
3) setup xinet.d
edit /etc/xinetd.d/pop3 and add:
# default: on
# description: pop3
service pop3
{
log_on_success += DURATION USERID
log_on_failure += USERID
port = 110
socket_type = stream
user = root
server = /usr/sbin/vm-pop3d
server_args = -t 600
wait = no
nice = 10
}
4) restart xinetd:
/sbin/service vm-pop3d stop      #(if its running)
/sbin/service xinetd restart