I was implementing System Center Operations Manager in a project at a customer for monitoring Exchange.
After loading the Exchange Management Pack, a bunch of errors like these were logged:
The Ehlo options for the client proxy target did not match while setting up proxy for user on inbound session 08D2F00F25C773B2. The critical non-matching options were . The non-critical non-matching options were . Client proxying will continue.
This error is logged for servers holding the mailbox role, even though it states Hub Transport in the source (that is no longer a standalone role in Exchange 2013).
So, looking at the alert description we can see it somehow relates to max size, and is generated in response to the EHLO options when a test connection is made to the server in question.
To dig into this, we need to determine the what the maximum message size defined in the Exchange organization is. This can be done using an Exchange Management Shell with this command:
Get-TransportConfig | ft maxsendsize, maxreceivesize
This lists the sizes configured for the Exchange organization.
Next, we need to determine which receive connector is configured with the different limit. This can be done by either looking at the receive connectors on the server listed in the error or running a command to list all receive connectors in the organization and correct those who deviate:
Get-ReceiveConnector | ft name, maxmessagesize
Examine the output, find the receive connector in question and correct its message size restriction. Or use this command to find all receive connectors with the deviating limit and correct them at the same time. Change the MB limit to fit your need.
Get-ReceiveConnector | Where-Object {$_.maxmessagesize -ne 35MB} | set-receiveconnector -maxmessagesize 35MB
Restart the Exchange Transport Service and voila, the error will go away.
