If it was working before but not now maybe the email address or the filename is the issue. The error looks like the scan template is the problem, so maybe there's an escape character.
What device are you using? Does the error occur consistently?
I a customer that I have setup with a scan to email button from the app studio. It has been working fine until recently. When you choose the button everything looks normal until you hit the scan button. Once you do that you get the following error.
Any Ideas?