AAMail Reverse DNS

2013/09/10 15:25

1. What is reverse DNS?

For example, "test@yaozhi.cn" sends an email to "hi@163.com".

Firstly, after 163 mail server receiving this email, and check the header document of the email, which will tell you this email was sent via which IP address.

Then, 163 mail server will reverse DNS according to this IP address. If the result shows that this IP address is corresponding to the domain name of "yaozhi.cn", then 163 mail server will accept this email. Otherwise, 163 mail server will reject it.

2. Why you need to reverse DNS?

2.1 To improve the success rate of sending mails.

If you do not reverse DNS, then the mail server, such as Sina, will reject the mails which were sent from this domain. Even if it is able to send mails, these mails will be likely to be sent to the "Spam".

2.2 To improve the ability of anti-spam.

Currently, most of the spammers use dynamic IP address or unregistered domain name to send spams to avoid tracking. So if the mail server has made "reverse DNS" records, then it can reject the mails which were sent from dynamic IP and the unregistered domain name, therefore, it greatly reduced the amount of spams.

3. How to set reverse DNS?

Contact the IP provider (if your IP is provided by the telecommunications, then contact them. If your server is hosted, then contact the server hosting provider) to make reverse DNS records for your IP. Normally, reverse resolve your IP as your mail server corresponding mx record.