I have been finding this more and more. If you are using forms on your websites and sending those responses to an emaill that is not part of that domain. (ie.
yourdomain.com is sending the form emails to
your...@gmail.com) There is a large likelihood that that email will go to spam, especially if the form was completed on a mobile phone.
So be sure to create any email, like
in...@yourdomain.com for your forms. You can always forward that email to any email address in your cplanel.