When you try to receive mail that is over 10mb into an Exchange 2010 mailbox, the sender may receive this bounce back error.

Your Exchange 2010 server may need a few settings changed if you want to receive mail of this size.

Due to the way Exchange routes emails we found the following settings helpful if you are using a facility such as popcon to download incoming mail.

1. Organization Configuration ->Hub Tansport.
   Go to Global Settings -> Transport Settings
   Set the Maximum send and receive size to KB values that suit eg. 20480 for 20mb or 51200 for 50mb
   
2. Go to Server Configuration ->Hub Transport
   Go through the receive connectors one-by-one and right-click -> Properties
   
3. Set the Maximum message size to a size that suits such as 20480 for 20mb and click OK. DO this for all the receive connectors unless you have a special one that you use for a certain purpose and needs to remain lower.
   

Now the larger messages from outside your organisation should get to their destination mailboxes in your Exchange 2010 Server.