Migration Toolkit: "Attachment Size Exceeds the Allowable Limit"

The migration toolkit log shows errors on attachments: "Attachment size exceeds the allowable limit".  This is not a MTK limit but an Exchange limit.

See this Microsoft KB article that explains how to change the limit:  http://support.microsoft.com/kb/2813269

This article was originally published in the GWAVA knowledgebase as article ID 2236.