Forum Discussion
4.4.2 Message submission rate for this client has exceeded the configured limit (Exchange 2019)
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.
Hi MohannadGH,
The parameter MessageRateLimit sets the maximum messages per minute for POP3 or IMAP4 clients using SMTP. Clients exceeding this value get a transient error.
Although you've set MessageRateLimit to unlimited or 200, the issue persists. Confirm settings with
Get-receiveconnector | ft Name, messageratelimit
cmdlet to ensure all receive connectors are configured correctly.
If settings are correct and the problem persists, try restarting the Transport service.
Stop-Service MSExchangeTransportGet-Service MSExchangeTransportStart-Service MSExchangeTransportGet-Service MSExchangeTransport
If the issue continues, consider factors like back pressure, monitoring disk space and memory. If thresholds are surpassed, the server gradually stops new connections and messages.
Message rate limits and throttling | Microsoft Learn
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Kindest regards,
Leon Pavesic
(LinkedIn)
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?
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
MaxPerDomainOutboundConnections : 20
I doubled the the MaxConnectionRatePerMinute to 2400. This was enough to stop the servers from dropping the connection, and to look for the cause:
Set-TransportService -Identity "SRV1" -MaxConnectionRatePerMinute 2400
To be honest, the event should at least be a warning instead of an informational event, but hey, that's just me...
Hope this is helpfull for you
