How To Set Message Size Limits in Exchange

When set the message size limits for incoming and outgoing email & attachments size, Please take under consideration the other side message size limitation .

Change the defaults on the connectors by names, this example will set limit of 50mB for the receive connector & Send Connector :

Get-ReceiveConnector | fl name
Set-ReceiveConnector “CONNECTOR NAME” -MaxMessageSize 50Mb

Get-SendConnector | fl name
Set-SendConnector “CONNECTOR NAME” -MaxMessageSize 50Mb

Get-TransportConfig | ft MaxSendSize, MaxReceiveSize
Set-TransportConfig –MaxSendSize 50MB –MaxReceiveSize 50MB

You can also change those limits settings for each user, To get all the mailbox’s setting and set for individual mailbox limits :

Get-mailbox | ft Name, MaxSendSize, MaxReceiveSize

Set-Mailbox “test” –MaxSendSize 30MB –MaxReceiveSize 30MB

Additional information can be found here

Good Luck