Invalid email address when updating form and sending mail

Invalid email address when updating form and sending mail

I have an app that sends an email when a form is submitted and edited.  The email address is provided by the user when they submit their info.  When they submit their info, no error is given and the email is sent just fine.  However, when they edit the form and re-submit, an error is given about an "Invalid email address".  The specific email address is in the form: fname.lname@gmail.com
It seems to be the . (dot) that is causing the problems.