diff --git a/admin/templates/default/mailaccount.xet b/admin/templates/default/mailaccount.xet
index e06dfc0ebf..b95c209e4d 100644
--- a/admin/templates/default/mailaccount.xet
+++ b/admin/templates/default/mailaccount.xet
@@ -347,9 +347,7 @@
 				<row class="emailadmin_no_user dialogHeader2">
 					<description for="account_id" value="Valid for"/>
 					<hbox>
-						<menulist>
-							<menupopup type="select-account" id="account_id" onchange="app.admin.account_hide_not_applying" options="Everyone,both"/>
-						</menulist>
+						<select type="select-account" id="account_id" onchange="app.admin.account_hide_not_applying" options="Everyone,both" multiple="dynamic"/>
 						<buttononly label="Select multiple" id="button[multiple]" onclick="app.admin.edit_multiple" options="users"/>
 						<checkbox label="account editable by user" id="acc_user_editable"/>
 					</hbox>
diff --git a/api/js/etemplate/et2_widget_selectbox.js b/api/js/etemplate/et2_widget_selectbox.js
index e1fe9a24c1..ebe2a15d3b 100644
--- a/api/js/etemplate/et2_widget_selectbox.js
+++ b/api/js/etemplate/et2_widget_selectbox.js
@@ -25,6 +25,8 @@
 var et2_selectbox = (function(){ "use strict"; return et2_inputWidget.extend(
 {
 	attributes: {
+		// todo fully implement attr[multiple] === "dynamic" to render widget with a button to switch to multiple
+		//	as it is used in account_id selection in admin >> mailaccount (app.admin.edit_multiple method client-side)
 		"multiple": {
 			"name": "multiple",
 			"type": "boolean",
diff --git a/api/src/Etemplate/Widget/Select.php b/api/src/Etemplate/Widget/Select.php
index f09cbcea2e..e05079423c 100644
--- a/api/src/Etemplate/Widget/Select.php
+++ b/api/src/Etemplate/Widget/Select.php
@@ -23,6 +23,8 @@ use calendar_timezones;
  * eTemplate select widget
  *
  * @todo unavailable cats (eg. private cats of an other user) need to be preserved!
+ * @todo fully implement attr[multiple] === "dynamic" to render widget with a button to switch to multiple
+ *	as it is used in account_id selection in admin >> mailaccount (app.admin.edit_multiple method client-side)
  */
 class Select extends Etemplate\Widget
 {
@@ -148,7 +150,7 @@ class Select extends Etemplate\Widget
 				if ($child->type == 'option') $allowed[] = (string)$child->attrs['value'];
 			}
 
-			if (!$multiple ) $allowed[] = '';
+			if (!$multiple || $this->attrs['multiple'] === "dynamic") $allowed[] = '';
 
 			foreach((array) $value as $val)
 			{