Exchange 2007 and Exchange Server 2010: Microsoft Entourage 2008 for Mac, Web Services Edition, Microsoft Outlook 2011 for Mac
1.This version of Entourage for Mac uses the Microsoft Exchange Server 2007 Web services provider to send mail. To allow for larger attachments that you must change the MaxRequestLength in the web.config file. By default, the web.config file is located in the EWS Virtual directory Microsoft\Exchange Server\ClientAccess\exchweb\EWS will have the following entry, by default, the max request size is approximately 13MB
<httpRuntime maxRequestLength=”13280″ />
2.Change the item <httpRuntime maxRequestLength=”13280″ /> to <httpRuntime maxRequestLength=”X” /> where X is the desired value in KBs. for example, X will be approximately 50000 (50MB).