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Ironport to Exchange number of messages per connection limit

Customer configured Ironport c170 to send EUQ notifications to end users at regular intervals.

When such EUQ notification emails were sent, there are logs saying that "Incoming connection (ICID xxx) failed to receive mail. Number of messages received per connection exceeds limit."

I suspect that such limit is imposed by the exchange server. However I am not able to find the settings on exchange for such limit.

Any one has similar experience?

Thanks in advance.

Cisco Employee

Ironport to Exchange number of messages per connection limit

Hi Daniel,

On the Mail Flow Policy you will see  "ACCEPTED"  under this you will see something that says "Max. Messages  Per Connection:" by default it is set to 10 and also you can see "Max.  Recipients Per Message:" that by default is set to 50.

Something  to notice about this is that it is just an informational message for  the administrator so the actual cliente can reconnect and send the  messages that re missing.

You can see more details using the message tracking feature.


Luis Silva

"If you need PDI (Planning, Design, Implement) assistance feel free to reach us"

Luis Silva
Cisco Employee

Ironport to Exchange number of messages per connection limit


I could be wrong but Exchange has a limit to send 25 messages in a single connection. I believe this is what you are seeing. It seems your C170 is throttling your Exchange but that would have nothing to do with EUQ notifications. As you mention, there are ICIDs in your C170's logs which could indicate C170 is imposing the limits to Exchange.

In a standard scenario, Exchange's IP address should be listed in the RELAYLIST sender group of the HAT of your C170. That HAT should be in the listener for outgoing traffic, generally a private listener. The sender group should have RELAYED mail flow policy associated with it. If you manually created the sender group and policy, it is possible you have less messages per connection being accepted by the mail flow policy.

I would recommend you to review the whole log for the ICID and make sure you know the correct Sender Group/Mail Flow policy and IP address of the sender host so you can then decide to make any configuration change.

You could use:

> grep "ICID xxx" mail_logs

where xxx is the number for the ICID in question.

I hope this helps.



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