diff --git a/wp-admin/includes/ajax-actions.php b/wp-admin/includes/ajax-actions.php
index 08d9de44b6..caf6311168 100644
--- a/wp-admin/includes/ajax-actions.php
+++ b/wp-admin/includes/ajax-actions.php
@@ -197,16 +197,27 @@ function wp_ajax_autocomplete_user() {
 	$return = array();
 
 	// Check the type of request
-	if ( isset( $_REQUEST['autocomplete_type'] ) )
+	// Current allowed values are `add` and `search`
+	if ( isset( $_REQUEST['autocomplete_type'] ) && 'search' === $_REQUEST['autocomplete_type'] ) {
 		$type = $_REQUEST['autocomplete_type'];
-	else
+	} else {
 		$type = 'add';
+	}
+
+	// Check the desired field for value
+	// Current allowed values are `user_email` and `user_login`
+	if ( isset( $_REQUEST['autocomplete_field'] ) && 'user_email' === $_REQUEST['autocomplete_field'] ) {
+		$field = $_REQUEST['autocomplete_field'];
+	} else {
+		$field = 'user_login';
+	}
 
 	// Exclude current users of this blog
-	if ( isset( $_REQUEST['site_id'] ) )
+	if ( isset( $_REQUEST['site_id'] ) ) {
 		$id = absint( $_REQUEST['site_id'] );
-	else
+	} else {
 		$id = get_current_blog_id();
+	}
 
 	$include_blog_users = ( $type == 'search' ? get_users( array( 'blog_id' => $id, 'fields' => 'ID' ) ) : array() );
 	$exclude_blog_users = ( $type == 'add' ? get_users( array( 'blog_id' => $id, 'fields' => 'ID' ) ) : array() );
@@ -223,7 +234,7 @@ function wp_ajax_autocomplete_user() {
 		$return[] = array(
 			/* translators: 1: user_login, 2: user_email */
 			'label' => sprintf( __( '%1$s (%2$s)' ), $user->user_login, $user->user_email ),
-			'value' => $user->user_login,
+			'value' => $user->$field,
 		);
 	}
 
diff --git a/wp-admin/js/user-suggest.js b/wp-admin/js/user-suggest.js
index 130c3d1adf..0113ded0e9 100644
--- a/wp-admin/js/user-suggest.js
+++ b/wp-admin/js/user-suggest.js
@@ -8,17 +8,23 @@
 			position.my = 'right top';
 			position.at = 'right bottom';
 		}
-		$( '.wp-suggest-user' ).autocomplete({
-			source:    ajaxurl + '?action=autocomplete-user&autocomplete_type=add' + id,
-			delay:     500,
-			minLength: 2,
-			position:  position,
-			open: function() {
-				$( this ).addClass( 'open' );
-			},
-			close: function() {
-				$( this ).removeClass( 'open' );
-			}
+		$( '.wp-suggest-user' ).each( function(){
+			var $this = $( this ),
+				autocompleteType = ( typeof $this.data( 'autocompleteType' ) !== 'undefined' ) ? $this.data( 'autocompleteType' ) : 'add',
+				autocompleteField = ( typeof $this.data( 'autocompleteField' ) !== 'undefined' ) ? $this.data( 'autocompleteField' ) : 'user_login';
+
+			$this.autocomplete({
+				source:    ajaxurl + '?action=autocomplete-user&autocomplete_type=' + autocompleteType + '&autocomplete_field=' + autocompleteField + id,
+				delay:     500,
+				minLength: 2,
+				position:  position,
+				open: function() {
+					$( this ).addClass( 'open' );
+				},
+				close: function() {
+					$( this ).removeClass( 'open' );
+				}
+			});
 		});
 	});
-})( jQuery );
\ No newline at end of file
+})( jQuery );
diff --git a/wp-admin/js/user-suggest.min.js b/wp-admin/js/user-suggest.min.js
index a9529f0268..9caf1e5f42 100644
--- a/wp-admin/js/user-suggest.min.js
+++ b/wp-admin/js/user-suggest.min.js
@@ -1 +1 @@
-!function(a){var b="undefined"!=typeof current_site_id?"&site_id="+current_site_id:"";a(document).ready(function(){var c={offset:"0, -1"};"undefined"!=typeof isRtl&&isRtl&&(c.my="right top",c.at="right bottom"),a(".wp-suggest-user").autocomplete({source:ajaxurl+"?action=autocomplete-user&autocomplete_type=add"+b,delay:500,minLength:2,position:c,open:function(){a(this).addClass("open")},close:function(){a(this).removeClass("open")}})})}(jQuery);
\ No newline at end of file
+!function(a){var b="undefined"!=typeof current_site_id?"&site_id="+current_site_id:"";a(document).ready(function(){var c={offset:"0, -1"};"undefined"!=typeof isRtl&&isRtl&&(c.my="right top",c.at="right bottom"),a(".wp-suggest-user").each(function(){var d=a(this),e="undefined"!=typeof d.data("autocompleteType")?d.data("autocompleteType"):"add",f="undefined"!=typeof d.data("autocompleteField")?d.data("autocompleteField"):"user_login";d.autocomplete({source:ajaxurl+"?action=autocomplete-user&autocomplete_type="+e+"&autocomplete_field="+f+b,delay:500,minLength:2,position:c,open:function(){a(this).addClass("open")},close:function(){a(this).removeClass("open")}})})})}(jQuery);
\ No newline at end of file
diff --git a/wp-admin/network/site-new.php b/wp-admin/network/site-new.php
index 672d7e869e..8765ab98c3 100644
--- a/wp-admin/network/site-new.php
+++ b/wp-admin/network/site-new.php
@@ -106,6 +106,8 @@ if ( isset($_GET['update']) ) {
 $title = __('Add New Site');
 $parent_file = 'sites.php';
 
+wp_enqueue_script( 'user-suggest' );
+
 require( ABSPATH . 'wp-admin/admin-header.php' );
 
 ?>
@@ -138,7 +140,7 @@ if ( ! empty( $messages ) ) {
 		</tr>
 		<tr class="form-field form-required">
 			<th scope="row"><?php _e( 'Admin Email' ) ?></th>
-			<td><input name="blog[email]" type="text" class="regular-text" title="<?php esc_attr_e( 'Email' ) ?>"/></td>
+			<td><input name="blog[email]" type="text" class="regular-text wp-suggest-user" data-autocomplete-type="search" data-autocomplete-field="user_email" title="<?php esc_attr_e( 'Email' ) ?>"/></td>
 		</tr>
 		<tr class="form-field">
 			<td colspan="2"><?php _e( 'A new user will be created if the above email address is not in the database.' ) ?><br /><?php _e( 'The username and password will be mailed to this email address.' ) ?></td>