dovecot - pop3login problem with huge user from the same ip

Dear,

here we have a centos 6.4, with latest ispconfig installed.
And dovecot 2.0

Problem is with an email domain with several mailbox (around 90) and all the user that connect via pop3, from the same IP.

It's look like that when all the user (or most of them) connect to the same time, happen a timeout that not permit any other new login.

I have change the configuration file (/etc/dovecot/dovecot.conf) adding on the top of them the variable mail_max_userip_connections setup to 120 (instead the default 10). But the problem remains the same.

So i have look deeper into the dovecot documentation and i have found that:

http://wiki2.dovecot.org/LoginProcess

that basically says to setup this one:

service imap-login {
service_count = 0
#client_limit = $default_client_limit
#process_min_avail = 0
#vsz_limit = 64M
}
service pop3-login {
service_count = 0
}

here the problem, is that i cannot understand on where put this configuration data. Because. If i try to put them on dovecot.conf file, and restart the daemon, nothign happen. Instead, if I try to put them on dovecot/conf.d/10-master.conf, and then restart nothing happen again (at lest verifying with doveconf -n these new configuration value are not taken).

What's wrong there?

Thank's

 

Ok, i have ended up with:

mail_max_userip_connections = 300

service auth {
[...]
client_limit = 7548
}
service anvil {
client_limit = 5503
}
service imap-login {
client_limit = 1000
process_limit = 500
}
service pop3-login {
client_limit = 1500
process_limit = 500
service_count = 0
}

in this way i have managed to reach almost 30 connection at the same time with the same IP.
Any suggestion in order to increase this value?

Thank's