Save Sent email to email account ‘Sent Items’ folder

I’m building a form which sends an email to me and the person that filled in the form, in order to check the email is being sent to them I would like all outbound emails to go via the local email acount (cPanel) so I can view them in the Sent folder.
During testing one of the submissions has resulted in a single email in the Sent folder, but nothing since.
What do I need to do to get this working?
Thanks