网易邮箱 iOS 客户端 Gmail 账号拒发发向 solidot.org 的邮箱？

发送邮件后收到 Google 的报错邮件：

Delivery to the following recipient failed permanently:

[email protected]

Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain solidot.org by mx.mail.ym.163.com. [123.58.178.51].

The error that the other server returned was:
551 5.1.1 recipient is not exist.

不知道是网易的原因，还是 Solidot 的原因...