If you select the Perform Reverse DNS Lookup for Incoming Messages option, the SMTP service tries to verify that the client’s IP address matches the host and domain that is submitted by the client in the EHLO/HELO command. If the reverse DNS lookup is successful, the RECEIVED header remains intact. If the verification is unsuccessful, "unverified" appears after the IP address in the RECEIVED header of the message. If the reverse DNS lookup fails, "RDNS failed" appears in the RECEIVED header of the message.
---通过这个KB来看,这个反向DNS并不和我们说的PTR一样,他只对IP对应EHLO和HELO的信息的域是否在DNS有效。所以你可能会遇到这种情况。
msExchSmtpPerformReverseDnsLookup 属性配置为不对传入邮件执行反向 DNS 查找。如果 Exchange Server 分析工具发现该属性设置为 True,则会显示警告;
---你有没有这个警告的具体信息,我猜是不是因为启用后会引起性能问题所以提出警告。不过要具体的信息才知道。