Notification Attachment fails when file is too large

Summary

It appears that the new feature to allow attachments to notifications has an attachment size limit

Content

We have had the oic.ics.console.notification-attachment feature enabled on our DEV and Production environments.  For the most part this feature is behaving as expected and is a very valuable enhancement to our notification capabilities.  

The one behavior that is not as expected is when the attachment file gets too large the email fails to be sent and no error message is generated.  The only indication of the error is the notification icon is turned red in the process flow. 

How large is too large?  We cannot determine the size limit because the information/error is not provided.