Scheduled Service Change: Lower Max Message Size.
Systems will only accept smaller email file sizes
There is no workaround for this issue
In order to match with the new message size limits we will be implementing with Exchange 2010 SP2 (scheduled for 7/15/12), we will also decrease the maximum message size on the appropriate mail routers (router1-4,router9-10, alva01-02). The new max message size will be 25MB.