seeking optimal smtp_psa file settings

[CliveL]

Qmail SMTP stopped yesterday and the logs showed

plesk xinetd[12387]: refused connect from IP due to excessive load.

By removing the below lines from smtp_psa everything is back to normal

max_load = 5
per_source = 2

I was wondering if anyone could share their optimal settings for the smtp_psa file.
Thank you.

 

[IgorG]

There are no these lines in default smtp_psa file:

-bash-3.2# cat /etc/xinetd.d/smtp_psa
service smtp
{
socket_type = stream
protocol = tcp
wait = no
disable = no
user = root
instances = UNLIMITED
env = SMTPAUTH=1
server = /var/qmail/bin/tcp-env
server_args = -Rt0 /var/qmail/bin/relaylock /var/qmail/bin/qmail-smtpd /var/qmail/bin/smtp_auth /var/qmail/bin/true /var/qmail/bin/cmd5checkpw /var/qmail/bin/true