Having trouble sending out via Mac Mail when connected to Exchange 2013 can't send anything over 10MB. I've used this resource: http://technet.microsoft.com/en-us/library/hh529949%28v=exchg.150%29.aspx
The Exchange 2013 default settings should allow for a 10MB(actually 64MB - 33%) file to be transferred via EWS.
I've checked organizational limits, connector limits, server/protocol limits, and user limits.
Organizational Limits:
[PS] C:\Windows\system32>Get-TransportConfig | select Size
MaxDumpsterSizePerDatabase : 150 MB (157,286,400 bytes)
MaxReceiveSize : 100 MB (104,857,600 bytes)
MaxSendSize : 100 MB (104,857,600 bytes)
ExternalDsnMaxMessageAttachSize : 10 MB (10,485,760 bytes)
InternalDsnMaxMessageAttachSize : 10 MB (10,485,760 bytes)
TransportRuleSizeLimit : 4 KB (4,096 bytes)
:Connector Limits::
[PS] C:\Windows\system32>get-receiveconnector | select Identity, Size
Identity MaxHeaderSize MaxMessageSize SizeEnabled
EX0001\Default EX0001 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) EnabledWithoutValue
EX0001\Client Proxy EX0001 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
EX0001\Default Frontend EX... 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
EX0001\Outbound Proxy Fron... 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
EX0001\Client Frontend EX0001 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
EX0002\Default EX0002 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) EnabledWithoutValue
EX0002\Client Proxy EX0002 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
EX0002\Default Frontend EX... 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
EX0002\Outbound Proxy Fron... 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
EX0002\Client Frontend EX0002 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
EX0001\Internet MX01 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
EX0002\Internet MX02 128 KB (131,072 bytes) 100 MB (104,857,600 bytes) Enabled
Server/Protocol Limits:
*These remain the defaults
Outlook Web App 35 MB
Exchange ActiveSync 10 MB
Exchange Web Services 64 MB
User Limits
Max Send / Receive user limits are specified as 100000kb (~100MB)