Forum Discussion
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 emails per minutes.
I investigated the issue and found out that there is only one receive connector in my environment that has the scope of 587 which is the a default connector "Client Frontend <ServerName>" , I noticed that the MessageRateLimit for this receive connector is set to default which is 5, the MessageRateLimit as shown in Microsoft Article refers to the maximum number of messages per minute that can be sent by a single source, which makes sense that the application has limitation of 5 emails per minutes.
Furthermore, I changed the MessageRateLimit to unlimited and the issue still occured, even when setting it to 200 for example, it still sends only 5 per minute.
Any idea what might be the case here, and if there is any possible solution? or if the limitation is the default behavior which cannot be changed?
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.
5 Replies
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.
This helped me a lot but the results measured are not one for one. It looks like some type of calculation between the 2 settings.
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, messageratelimitcmdlet 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 LearnPlease click Mark as Best Response & Like if my post helped you to solve your issue.
This will help others to find the correct solution easily. It also closes the item.If the post was useful in other ways, please consider giving it Like.
Kindest regards,
Leon Pavesic
(LinkedIn)- 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?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
