I have recently installed an Exchange Server 2013.
I have setup in all Send and Receive connectors a maximum message size of 100MB, through the EAC.
That works fine for Outlook.
However, in OWA, when trying to attach anything larger than 5MB, I get:
"The following files weren't attached because adding them would cause the message to exceed the maximum size limit of 5 MB"
I found this article explaining how to change the message and attachment size limit for OWA, using notepad (really) to edit manually 27 (yes, 27!!)
entries in a bunch of config files.
I went thoroughly through all of them, changed them, and rechecked each one.
I ran a IISRESET after that.
I still have the problem.
I don't know where that '5MB' limit is coming from
, but threre wasn't anything in the config files set to 5MB before the change (they were settings to 10MB, 35MB and 64MB, I think) so I'd guess this limit is coming from yet another location that I didn't find yet.