mailto 自动生成电子邮件链接，并根据选项决定是否对地址信息编码. 电子邮件地址编码使得网络嗅探程序难以收集到电子邮件地址信息.
技术要点: 尽管可以使用 hex 进制编码，但 javascript 已经算得上是很彻底的编码形式了.
eg:
{mailto address="me@domain.com"}
{mailto address="me@domain.com" text="send me some mail"}
{mailto address="me@domain.com" encode="javascript"}
{mailto address="me@domain.com" encode="hex"}
{mailto address="me@domain.com" subject="Hello to you!"}
{mailto address="me@domain.com" cc="you@domain.com,they@domain.com"}
{mailto address="me@domain.com" extra='class="email"'}
输出:
<a href="mailto:me@domain.com" >me@domain.com</a>
<a href="mailto:me@domain.com" >send me some mail</a>
<SCRIPT language="javascript">eval(unescape('%64%6f%63%75%6d%65%6e%74%2e%77%72%6
9%74%65%28%27%3c%61%20%68%72%65%66%3d%22%6d%61%69%6c%74%6f%3a%6d%65%40%64%6f%6d%
61%69%6e%2e%63%6f%6d%22%20%3e%6d%65%40%64%6f%6d%61%69%6e%2e%63%6f%6d%3c%2f%61%3e
%27%29%3b'))</SCRIPT>
<a href="mailto:%6d%65@%64%6f%6d%61%69%6e.%63%6f%6d" >me@d&
#x6f;main.com</a>
<a href="mailto:me@domain.com?subject=Hello%20to%20you%21" >me@domain.com</a>
<a href="mailto:me@domain.com?cc=you@domain.com%2Cthey@domain.com" >me@domain.com</a>
<a href="mailto:me@domain.com" class="email">me@domain.com</a>
