4.4.2 Message submission rate for this client has exceeded the configured limit (Exchange 2019)

Hello There, I have an application which relays emails through the Exchange 2019. The application uses SMTPs on port 587, when I try to send a test email, I am experiencing a limitation of 5 e...

Exchange Server

MohannadGH
Jan 03, 2024
Resolution: The issue was related to MessageRateLimit, however, we were looking at the wrong part. The receive connector "Client Frontend " is indeed responsible for the email relay for the port 587. However, this is not the only connector which is being used during the process of email delivery. After a thorough investigation, we found out that the "Client Proxy " receive connector is also used in the process and the MessageRateLimit must be also increased. Finally, after increasing the client proxy receive connector MessageRateLimit, the issue was resolved and email limitation was fixed.

MohannadGH

Brass Contributor

Dec 17, 2023

Hello There,

Thank you for your feedback.

All the mentioned steps has been tested, but unfortunately nothing helped with the issues.

Could it be related to a limitation from the Exchange side?

Nikooo

Copper Contributor

Mar 26, 2025

I had a similair e-mail problem with appliances getting the 4.4.2 rate limit from our Exchange servers when trying to send mail. Took a while to find that the event to look for was the Informational Event 1030 - MSExchangeTransport (the eventlog was flooded with devices constantly connecting, and causing the issue of the exceeded connections):

The connection from IP address [xxxx] is being dropped. The rate of connections from this IP address has exceeded the configured limit '1200' per minute.

Get-TransportService | Format-List Name,MaxConcurrent*,MaxConnection*,Max*OutboundConnections

Name : SRV1

MaxConcurrentMailboxDeliveries : 20

MaxConcurrentMailboxSubmissions : 20

MaxConnectionRatePerMinute : 1200

MaxOutboundConnections : 1000

MaxPerDomainOutboundConnections : 20

Name : SRV2

MaxConcurrentMailboxDeliveries : 20

MaxConcurrentMailboxSubmissions : 20

MaxConnectionRatePerMinute : 1200

MaxOutboundConnections : 1000