This problem plagued us for the last couple of days. One of our vendors sent us a 11 MB Acrobat catalog as an attachment to a regular email message and Microsoft’s Exchange was not letting it through. I thought that the personal sending and receiving limits would override the global limits. This would allow a few people to receive large attachments. Microsoft’s KB 28572 set me straight.
These global settings affect all Exchange recipients. If a recipient has configured their own personal sending or receiving message size limits, the global message size limits override the individual message size limits of the mailbox.