EXCHANGE   Exchange – 421 4.4.2 Message submission rate for this client has exceeded the configured limit



An application started to log random error messages when trying to send emails through one of my Exchange receive connectors. So I checked and filtered the "Client Frontend" receive connector that showed at certain minute 6 email deliveries.

2016-01-12T17:49:00.530Z,EXCHANGESRV\Client Frontend EXCHANGESRV,08D31A7027871E90,3,10.20.20.5:587,10.10.6.10:59301,<,EHLO server1,
2016-01-12T17:49:00.811Z,EXCHANGESRV\Client Frontend EXCHANGESRV,08D31A7027871E90,43,10.20.20.5:587,10.10.6.10:59301,*,,Proxy session was successfully set up. Session for application1 will now be proxied

2016-01-12T17:49:01.155Z,EXCHANGESRV\Client Frontend EXCHANGESRV,08D31A7027871E92,3,10.20.20.5:587,10.10.6.10:59302,<,EHLO 
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