How to setup ptr record for mail server

A PTR (Pointer) record is a type of DNS record that points a domain name to an IP address. In the context of a mail server, a PTR record is used to verify the authenticity of an email server by checking the IP address against the domain name. Here's a step-by-step guide on how to set up a PTR record for your mail server:

Prerequisites:

  1. You have a domain name registered with a registrar (e.g., GoDaddy, Namecheap, etc.).
  2. You have a mail server (e.g., Postfix, Exim, etc.) set up and running.
  3. You have a static IP address assigned to your mail server.

Step 1: Determine the IP address of your mail server

Find the IP address of your mail server. This can be done by:

Step 2: Create a PTR record

Create a PTR record in your DNS zone file or use a DNS management tool to create a new record. The format of a PTR record is:

<ip address>.in-addr.arpa. IN PTR <domain name>

Replace <ip address> with the IP address of your mail server, and <domain name> with the domain name of your mail server (e.g., mail.example.com).

For example, if your IP address is 192.0.2.1, your PTR record would be:

1.2.0.192.in-addr.arpa. IN PTR mail.example.com

Step 3: Update your DNS zone file or DNS management tool

Update your DNS zone file or use your DNS management tool to add the new PTR record. Make sure to save the changes.

Step 4: Verify the PTR record

Use a tool like dig or nslookup to verify that the PTR record has been updated correctly. Run the following command:

dig +short <ip address>.in-addr.arpa. PTR

Replace <ip address> with the IP address of your mail server. The output should match the domain name of your mail server (e.g., mail.example.com).

Step 5: Configure your mail server

Configure your mail server to use the PTR record. This may involve updating your mail server's configuration files or using a mail server management tool.

Example configuration for Postfix:

In your Postfix configuration file (/etc/postfix/main.cf or equivalent), add the following lines:

mydestination = mail.example.com myhostname = mail.example.com myorigin = $myhostname

Restart your Postfix service to apply the changes.

Example configuration for Exim:

In your Exim configuration file (/etc/exim.conf or equivalent), add the following lines:

domainlist local_domains = mail.example.com hostlist relay_from_hosts = +relay_from_hosts

Restart your Exim service to apply the changes.

By following these steps, you should now have a PTR record set up for your mail server. This will help improve the deliverability of your emails and reduce the risk of being flagged as spam.