今天惯例开ichat和朋友聊gtalk，发现自己居然还有一个mac.com的帐号，查了一下密码记录发现和me.com的不一样，但是当我在ichat的偏好设置里将mac.com的密码设好，me.com也跟着自动换成和mac.com一样的密码了，反之亦然。话说这mac.com帐号到底是个什么东西啊？苹果搞那么多帐号再加上itunes的几个，太烦躁了。

mac。com的是很早的了
现在应该是apple id为主流

看了一下貌似mac.com转去MobileMe了？
Summary
If you were a .Mac subscriber before the launch of MobileMe, you had a username@mac.com email address.  Now that we have converted to MobileMe, you have also been granted a username@me.com address.  These email addresses are aliases of one another, so they are one and the same and share the same inbox.  You can choose to use either email address to send and receive mail on your computer, iPhone, or iPod touch and set up your MobileMe Contact and Calendar syncing.

尝试向mac.com发email，结果显示查无此人发送失败，我的ichat里mac.com也登录不上去，重新添加me.com帐户也不行，太2了！

再次试验，打开VPN，于是一切都正常了，这麻痹原来是GFW在作祟啊！

MobileMe就是现在的.Mac，楼主的问题估计是没主动做数据迁移导致的
估计iCloud代替MobileMe之后还会有一堆这样的问题。。