$to = 'a1@b.com, a2@b.com, a3@b.com';
$subject = 'The Subject of your e-mail';
$message = 'The Content of your e-mail';
$headers = array('Content-Type: text/html; charset=UTF-8');
wp_mail( $to, $subject, $message, $headers );
$to = 'a1@b.com, a2@b.com, a3@b.com';
$subject = 'The Subject of your e-mail';
$message = 'The Content of your e-mail';
$headers = array('Content-Type: text/html; charset=UTF-8');
wp_mail( $to, $subject, $message, $headers );