What does the error “421 4.3.2 Connection rate limit exceeded” mean?
In case you use sendmail try just to add relay into the access file e.g.
error before change
Apr 3 11:01:40 posta sm-mta[18136]: ruleset=check_relay, arg1=[188.123.111.4], arg2=188.123.111.4, relay=[188.123.111.4], reject=421 4.3.2 Connection rate limit exceeded.
vi /etc/mail/access
188.123.111.4 RELAY
cd /etc/mail/
makemap hash access < access
/etc/init.d/sendmail restart
test email and check /var/log/mail.log good luck 🙂
The Grande email systems utilize throttling mechanisms to mitigate the negative effects of various denials of service, intentional or otherwise. The system will permit up to 4 connections in a given one minute period to any host, however they may only have 2 simultaneous connections at any given time during that period. If either threshold is exceeded, the mail server will temporarily refuse subsequent connections from that host for 60 seconds at which point redelivery can then be attempted. If you are receiving this error, you are likely using mailing list software which cannot decipher the temporary fail codes. If so, you will need to set your software to slow down its delivery rate and/or reduce the number of active connections per remote host.
