The organizational send and receive size limits apply to all Exchange servers in the Organization. The default is 10MB.
You can modify the organizational message size limits using the Set-TransportConfig cmdlet from the Exchange shell:
Set-TransportConfig -MaxReceiveSize 40MB -MaxSendSize 40MB
In Exchange 2007 SP1 and later, you can also set the organizational message size limits using the EMC by going to Organization Configuration | Hub Transport | Global Settings tab | Transport Settings | properties | General tab.
Receive Connector limit
To modify the maximum message size on a Receive Connector using the Exchange console, select Server Configuration | Hub Transport | select a Hub Transport server | Receive Connectors -> select a connector | Properties | General tab.
To set ReceiveConnector limit using the shell:
Set-ReceiveConnector “CONNECTOR NAME” -MaxMessageSize 40Mb
Send Connector limit
Send Connectors are used for sending outbound messages to the internet or particular address spaces (domains). Edge Transport servers also have a Send Connector to send inbound messages to Hub Transport servers in an AD Site. To modify the maximum message size on Send Connectors, select Organization Configuration | Hub Transport | Send Connectors -> select connector | Properties | General tab.
To set SendConnector limit using the shell:
Set-SendConnector “CONNECTOR NAME” -MaxMessageSize 40Mb