Postfix limit

Postfix a way to limit the frequency of brute force?
In file /usr/local/etc/postfix/main.cf place something like the following:
Code:
...
# RATE THROTTLING
smtpd_client_connection_rate_limit = 20
smtpd_error_sleep_time = 10s
smtpd_soft_error_limit = 3
smtpd_hard_error_limit = 5
...

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