В SDK написано 2147483647. Ну если точно, то так: The default maximum of an attachment that is processed on the Microsoft Dynamics CRM server is 5 MB. You can increase the size limit by specifying a new value in the organization.maxuploadfilesize property. However, an attachment size cannot exceed the maximum HTTP request size (the default is 16MB). For the change to take effect, reset Internet Information Services (IIS). To do this, click Start, click Run, type iisreset, and then click OK.
Почему на конце 7 я так и не понял. Видимо с нуля считают.
