Como Validar e-mails?

[bet]

<pre>
&lt;html&gt;
&lt;head&gt;
&lt;title&gt; New Document &lt;/title&gt;

&lt;script LANGUAGE=&quot;JavaScript&quot;&gt;

function Validar(form)
{
if (form.Email.value == &quot;&quot;) {
alert(&quot;Por favor ingrese su dirección de e-mail&quot;);
form.Email.focus();
return false;
}

if (form.Email.value.indexOf('@', 0) == -1 || form.Email.value.indexOf('.', 0) == -1) {
alert(&quot;Dirección de e-mail inválida&quot;);
form.Email.focus();
return false;
}

}

&lt;/script&gt;
&lt;/head&gt;

&lt;body bgcolor=&quot;#FFFFFF&quot;&gt;
&lt;form method=post action=&quot;&quot; onSubmit=&quot;return Validar(this);&quot;&gt;
Mail: &lt;input type=&quot;text&quot; name=&quot;Email&quot;&gt; &lt;input type=&quot;submit&quot;&gt;
&lt;/form&gt;
&lt;/body&gt;
&lt;/html&gt;
</pre>

<hr noshade size=1 color="#000000"><img src="http://www.gograph.com/Images-8712/ClipArt/cat03.gif" height="50" border=0 align="absmiddle"> <font size="2" face="verdana" color="#000000">bet[/CODE]