Use this code to format a field value or change the field value that displays in the email notification.

add_filter('frm_email_value', 'frm_email_val', 15, 3);

function frm_email_val($value, $meta, $entry){

  if($meta->field_id == 25){ //change 25 to the ID of your field

    $value = "My custom email content"; //change the value here

  }

  return $value;

}

Use the code below to replace an ampersand character reference with a plain ampersand. Replace 25 with the ID of the field you want to modify.

add_filter( 'frm_email_value', 'frm_replace_ampersand', 15, 3);

function frm_replace_ampersand( $value, $meta, $entry ){

  if ( $meta->field_id == 25 ) { //change 25 to the ID of your field

    $value = str_replace("&","&",$value);

  }

  return $value;

}