I was working on a solution on my test system this morning and received the following error while attempting to send an email.

 

So, the question is: Which exactly was invalid?

My Visibility?

My Modification of said Visibility?

Or my access level that would not allow me to Modify my Visibility?

 

Those are all questions that I just didn't feel like answering at 6:00am this morning, but I guess I'll have to figure it out sometime. :)