收到很多的退信，是什么意思呢？？

leaflet

我建了一个邮箱，向外发邮件。经过测试，126.com和163.com都能收到，sina不行。今天看邮箱里有很多信。标题都是postmaster undeliverable mail<br>
以下是我复制的一些信的内容，请大家帮我看看是咋回事呢？<br>
<br>
undeliverable to xuhongming@vip.citiz.net<br>
<br>
Server response to MAIL FROM:<br>
557 sorry, you're NOT allow to use this SMTP Server to relay your email (#5.7.2)<br>
<br>
<br>
Unknown user: 2012141@163.com<br>
<br>
RCPT TO generated following response:<br>
550 <2012141@163.com>: User status is locked.<br>
<br>
<br>
<br>
Unknown user: lixiang0421@hotmail.com<br>
<br>
RCPT TO generated following response:<br>
550 Requested action not taken: mailbox unavailable<br>
<br>
<br>
<br>
Unknown user: lixiang0421@hotmail.com<br>
<br>
RCPT TO generated following response:<br>
550 Requested action not taken: mailbox unavailable<br>
<br>
<br>
Unknown host: wang_tian_1@126.com<br>
<br>
谢谢了！！<br>

leaflet

顶楼的sina帖子从头看到尾，没看出解决方法。。。关于设置方面的，还有我这个好像除了sina其它也有收不到的

钉子

如果大多数邮箱都能接收的话。新浪的问题要特别处理一下，看看置顶的帖子