php mail() two copies sent

Question

I have a simple message that I send using php mail(). The code used:

//recipient info
$to = \"$bookernavn <$mail>\";
$from = \"Visens Venner Hillerød &         


        

Answer 1

You don't check to see if the form has been submitted so a browser refresh will send the form data again and cause the mail to be sent again. This also happens when a user presses the back button.

After the email is sent you need to do a 303 redirect to prevent the re-submission. You can redirect to the same page if you'd like.

This is called the Post/Redirect/Get pattern.

mail(...);
header('Location: /some-page-php', true, 303);
exit;