How to make email body all caps?

I would like the confirmation email I (the admin) receive to be in all caps. I’m trying to do that with this code:

‘add_action( ‘wpcf7_before_send_mail’, ‘wpcf7_all_caps_email’, 10, 3 );

function wpcf7_all_caps_email( $WPCF7_ContactForm, $abort, $submission ) {
$mail = $WPCF7_ContactForm->prop( ‘mail’ );
$mail[‘body’] = strtoupper( $mail[‘body’] );

// Save the email body.
$WPCF7_ContactForm->set_properties(
array(
‘mail’ => $mail,
)
);
}`

But the email that is being sent doesn’t have the values the user enters. It looks like this:

FROM:
[YOUR-NAME]

EMAIL:
[YOUR-EMAIL]

PHONE:
[YOUR-PHONE]

COMPANY: (EMPTY IF NOT ENTERED)
[COMPANY-NAME]

EVENT DATE:
[_FORMAT_EVENT-DATE "F JS Y"]

EVENT LOCATION INFORMATION:
[EVENT-ADDRESS]
[EVENT-CITY]

VENUE:
[VENUE-NAME]

NUMBER OF GUESTS:
[NUMBER-OF-GUESTS]

DELIVERY REQUESTED?
[DELIVERY]

MESSAGE:
[YOUR-MESSAGE]

REQUESTED ITEMS:

[YITH-REQUEST-A-QUOTE-LIST]

How do I do this? I searched for hours but I’m stuck.