<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.macromedia.com/2005/mxml" xmlns="*" height="100%" width="100%">
    <mx:Script>
        <![CDATA[
            public function email(str:String):Boolean {
                var pattern:RegExp = /(\w|[_.\-])+@((\w|-)+\.)+\w{2,4}+/;
                var result:Object = pattern.exec(str);
                if(result == null) {
                    return false;
                }
                return true;
            }
        ]]>
    </mx:Script>
    <mx:Panel width="100%" height="100%" title="Email Regex Validator">
        <mx:Form>
            <mx:FormItem label="Email Address:">
                <mx:TextInput id="emailAddress" width="100%" />
            </mx:FormItem>
            <mx:FormItem label="Email is valid:">
                <mx:Text id="valid" text="{email(emailAddress.text)}" width="100%" fontWeight="bold"/>
            </mx:FormItem>
        </mx:Form>
    </mx:Panel>
</mx:Application>