after.php

$email = 'ashfame@example.com';
$subject = 'Custom stuff email';
$email_heading = 'Custom Heading';
$email_content = ''; // whatever it is

ob_start();

do_action( 'woocommerce_email_header', $email_heading );

echo $email_content; // or simply have HTML markup outside PHP tags here

$email_content = ob_get_clean();

wp_mail( $email, $subject, $email_content );

before.php

$email = 'ashfame@example.com';
$subject = 'Custom stuff email';
$email_content = ''; // whatever it is

wp_mail( $email, $subject, $email_content );