Sent Items Update – the updated message is too large
If a message that is updated by Sent Items Update is too large, an exception may occur. This will typically be caused by a large attachment kn the message that is over several MB. As a result the message will not be updated.
In order to solve the problem, you need to modify the ExchangeWebService settings that is responsible for updating messages in Exchange mailboxes. This can be done by editing the web.config file for the EWS service. The default path for this file is:
C:\Program Files\Microsoft\Exchange Server\ClientAccess\exchweb\ews\web.config
If the file or EWS is not located in this address, open IIS manager, go to Web Sites, Default Web Sites, and EWS.
Right click and choose Properties. Read the location of the file.
Edit the web.config file using the Notepad. In the file search for (node) xml
<httpRuntime maxRequestLength="size in Kbytes"/>
Between the quotes "", provide the maximum size of the message that will be accepted by EWS.