退信内容：Recipient address rejected:ERS-QIL

退信原因：IP黑名单问题

解决方案：这个错误，是趋势网关黑名单IP拦截问题，ERS是Email Reputation Services的缩写，QIL是趋势动态IP黑名单库：The Dynamic Reputation Database or Quick IP List is a highly dynamic list and uses advanced detection techniques for attacks caused by botnets (zombie networks, SMTP malware, spyware). IP addresses are added and removed quickly due to the nature of the threat.直接到他们的网站查询解封下IP即可：https://www.ers.trendmicro.com