Thank you for your post.
Does the solution send email through the default email application? If so, what is the default email application on the clients machine? If you are sending via SMTP, what mail server is the message being sent?
For clarification, does the runtime solution crash when she sends the email? Or, does it crash as she is entering information into the Send Mail step?
Thank you for your post. I am contacting my client to get the answers to these questions. Thanks.