diff --git a/modoboa/extensions/webmail/static/webmail/js/webmail.js b/modoboa/extensions/webmail/static/webmail/js/webmail.js
index fc5af1b3a..a4e3c3240 100644
--- a/modoboa/extensions/webmail/static/webmail/js/webmail.js
+++ b/modoboa/extensions/webmail/static/webmail/js/webmail.js
@@ -993,7 +993,9 @@ Webmail.prototype = {
                 var $tr = $this.parent();
 
                 if (!plug.htmltable.is_selected($tr)) {
+                    var $input = $tr.find('#selection');
                     plug.htmltable.select_row($tr);
+                    $input.prop('checked', true);
                 }
 
                 var nmsgs = plug.htmltable.current_selection().length;
diff --git a/modoboa/static/js/jquery.htmltable.js b/modoboa/static/js/jquery.htmltable.js
index 3a615cf50..7b3c1c0b9 100644
--- a/modoboa/static/js/jquery.htmltable.js
+++ b/modoboa/static/js/jquery.htmltable.js
@@ -34,8 +34,10 @@
             $(document).on("keyup", "body", $.proxy(this.keyup, this));
         },
 
+        /**
+         * Effective change of a table row's state.
+         */
         _toggle_select: function($tr) {
-            this.last_selection = $tr;
             if ($tr.hasClass(this.options.tr_selected_class)) {
                 $tr.children('td[name=selection]').children('input').prop('checked', false);
                 $tr.removeClass(this.options.tr_selected_class);
@@ -51,14 +53,23 @@
             }
         },
 
+        /**
+         * Change the selection state of a given table row.
+         *
+         * Holding the shift key between two selections let users
+         * select all rows between those two locations.
+         *
+         * Holding the ctrl key between two selections let users make
+         * an additive selection.
+         */
         toggle_select: function(e) {
             var $tr = $(e.target).parents('tr');
 
             if (this.shift_pressed && this.last_selection) {
-                if ($tr.is(this.last_selection)) {
-                    $tr.children('td[name=selection]').children('input').prop('checked', true);
-                    return;
-                }
+                var start = this.last_selection;
+
+                this.clear_selection();
+                this.last_selection = start;
                 var itfunc = ($tr.index() >= this.last_selection.index())
                     ? "next" : "prev";
                 var $curtr = null;
@@ -66,7 +77,7 @@
                 if (this.prev_dir && itfunc != this.prev_dir) {
                     $curtr = this.last_selection;
                 } else {
-                    $curtr = this.last_selection[itfunc]("tr");
+                    $curtr = this.last_selection;
                 }
                 for (; $curtr.length; $curtr = $curtr[itfunc]("tr")) {
                     this._toggle_select($curtr);
@@ -79,19 +90,26 @@
             } else if (!this.ctrl_pressed && (!this.last_selection || !this.last_selection.is($tr))) {
                 this.clear_selection();
             }
+            this.last_selection = $tr;
             this._toggle_select($tr);
         },
 
+        /**
+         * Check if $row is selected or not.
+         */
         is_selected: function($row) {
             return $row.hasClass(this.options.tr_selected_class);
         },
 
+        /**
+         * Return the current selection. (jQuery object)
+         */
         current_selection: function() {
             return $("tr[class*=" + this.options.tr_selected_class + "]");
         },
 
-        /*
-         * Cancel the current selection
+        /**
+         * Cancel the current selection.
          */
         clear_selection: function() {
             this.last_selection = null;
@@ -102,10 +120,13 @@
             }
         },
 
-        /*
-         * Manually select a table row
+        /**
+         * Manually select a table row.
          */
         select_row: function($row) {
+            if (!this.last_selection) {
+                this.last_selection = $row;
+            }
             $row.addClass(this.options.tr_selected_class);
             if (this.options.tr_selected_event != undefined) {
                 this.options.tr_selected_event($row);