If notification emails sent to the same domain ([email protected]) that the website is hosted on (www.thisdomain.com). are not being received when a webform is filled out, this may occur if the email services is not hosted on the same server where the website is hosted. Then, if you using linux, make a change in "cpanel" to affect MX Record, because the Record is not set to Remote (by default), despite the fact the mail is not even handled here.
Full Article: https://www.drupal.org/node/2391817Im sure other people are dealing with this issue and frustrated, just making it more visible.