PROBLEM

You have configured the Simple Email Form module to send emails to your gmail account on Google.  The emails are not being received.  When you activate the "Send me a copy" feature, the emails appear OK in other email accounts outside of gmail.

SOLUTION

Google restricts automated emails being sent from a web server to gmail.  You will need to configure your Google gmail account to allow automated submissions!  Alternatively, use another email account outside of gmail to serve as a contact target.