Recipient Properties > Mail Flow Settings Tab > Message Size Restrictions (RTM)
Microsoft Exchange Server 2007 will reach end of support on April 11, 2017. To stay supported, you will need to upgrade. For more information, see Resources to help you upgrade your Office 2007 servers and clients.
Applies to: Exchange Server 2007
Use the Message Size Restrictions dialog box to specify the size limit for messages that are received by the recipient.
Receiving message size
Select the Maximum message size (in KB) check box to configure a receiving message size restriction for this recipient. Use the text box to type the maximum message size in kilobytes (KB) that the recipient is allowed to receive. The value range is 0 KB through 2,097,151 KB.
If another recipient attempts to send a message that is larger than the size specified, the message is returned to the sender with a descriptive error message.
Clear this check box to remove the any size restrictions for receiving messages.