In a multisite, you can create child sites. When you create a new child site, you fill in the title and the slug. And, you have to fill in your e-mail address, even if you are the network administrator.

If you enter an e-mail by hand, you may mistype. But, you can avoid such a risk. This code, shown below, automatically fill your e-mail address into the corresponding box, with an aid of jquery.

add_action( 'admin_footer-site-new.php', 'add_admin_email', 10);
function add_admin_email() {
    $mail = get_the_author_meta( 'user_email', 1 );
    if ( is_email($mail)) : ?>
<script language="javascript">
//<![CDATA[
jQuery(document).ready(function($){
$("input[name=blog[email]]").val("<?php esc_attr_e($mail); ?>");
});
//]]>
</script>
<?php endif;
}

NOTE: should not be activated on a single wordpress install.