Exchange Active Sync send limit
The message could not be sent
If you want to send an e-mail via ActiveSync, for example via an iPhone, that is larger than the set limit, you may get the message that the message could not be sent due to its size.
First, you have the option to adjust the size limit. To do this, navigate to the path
C: \ Program Files \ Microsoft \ Exchange Server \ V15 \ ClientAccess \ Sync
and opens the web.config. searches for the entry maxRequestLength = “10240“ and adjusts it.