How to limit recipient per message

[dangcongphung]

I want to limit recipient per message. I search on website and find some usefull information. Follow them, I configure in my main.cf
smtpd_recipient_limit = 3
smtpd_recipient_overshoot_limit = 1

After that, I send a test mail to 4 recipients from my local domain mail. This functions works, the server don't permit to send.
But when i send a test mail to 4 recipients from external domain mail (gmail). It doesn't works. My server permit to receive . It seem this message broken up into smaller lists. And pass my rule.
How I can limit recipient per message from outside domain mail ?
Pls help me
Thanks all

[soba@ukw.edu.pl]

postconf | grep -i recip

[soba@ukw.edu.pl]

smtpd_recipient_limit = 60
smtpd_recipient_overshoot_limit = 20
smtpd_client_recipient_rate_limit=40
#smtpd_recipient_limit = 300
smtpd_client_message_rate_limit = 0

for postfix 3

[dangcongphung]

someone help me plz

[gvillaran]

"But when i send a test mail to 4 recipients from external domain mail (gmail). "

thats not because yo are using the gmail smtp engine? if yes then the restriction should be set in gmail smtp engine and i think you cant do that

or im wrong?