Why Your Emails Need Reverse DNS & How to Set it Up in 2023

Avoid SPAM with Reverse DNS for Email Servers & APIs

Setting up Reverse DNS to send emails is important if you want to avoid the SPAM folder. The Reverse DNS lets email providers such as Gmail, Outlook, etc know that the domain on the email is accurate and trustworthy because only the domain manager would be able to set it up.

Why use Reverse DNS to send emails
Using Reverse DNS to Send Emails

What is Reverse DNS

Reverse DNS, sometimes referred to as rDNS, is a mapping system that resolves a domain name into an IP address. It works by taking an IP address and matching it with a unique hostname or fully qualified domain name (FQDN). This type of configuration can help to ensure deliverability when sending emails out from your applications that use SendGrid or Active Campaign’s API.

Why Does Email Need Reverse DNS

If you send out mass email campaigns through your web application, Reverse DNS ensures better deliverability. This will help improve the reputation of your email server and reduce the chances of emails being marked as spam or undeliverable. It also ensures that your emails are sent from a trusted source and not flagged as suspicious by other servers.

What is the difference between forward and reverse DNS

Forward DNS is where a hostname is resolved into an IP address, while reverse DNS works in the opposite direction where the IP address is resolved back to the domain. Forward DNS is used to match domain names with IP addresses so that web browsers can access websites on the internet. Reverse DNS does the same thing but matching IP addresses to domain names which helps verify emails sent from your server.

  • Web browsers Use Forward DNS to know where to actually send the user
  • Email providers use Reverse DNS to know the email comes from the right source

Benefits of using Reverse DNS When Sending Emails

The main advantage of using reverse DNS for sending emails is that it helps to establish trustworthiness in the eyes of receiving mail servers. By verifying an IP address against its associated domain name, mail servers will know exactly where the email originated from, helping to minimize the risk of it being marked as suspicious or potentially malicious. Additionally, having a unique hostname allows senders to customize their message headers which can be used to provide more information about the sender.

  • Establishes trustworthiness
  • Email providers knows the sender’s origin
  • Provides more information about the sender to email provider
  • Ensures that your email arrives in the inbox
  • Helps prevent the email from going into the email receiver’s spam folder.

How to setup Reverse DNS for Email Server

Setting up a reverse DNS for your email server is straightforward. You create a record with your DNS provider. Once complete, test it with a WHOIS lookup tool to verify it is correct. The final result should correspond with the expected domain name.

  • Log into your Domain Provider Control Panel
  • Go to the DNS Section
  • Update the desired records for your email service provider
  • Save the results
  • Test it using a WHOIS lookup tool (https://lookup.icann.org/en is good)
  • Verify that the results show as you expect.

How to setup Reverse DNS in SendGrid

SendGrid requires you to establish a valid reverse DNS record in order to send emails through their API. This process involves setting up an SPF, DKIM, and Domain Keys records as well as the necessary PTR or Pointer resource record. They have a helpful article on setting this up on their website: How to Setup Reverse DNS in SendGrid | Official Docs

Digging Deeper into SendGrid Email API.

Want to learn more about SendGrid? This is one of several articles where we’ve explored this email service in detail. Check out the following articles to go deeper and learn more about what is SendGrid and how to use it.

Reverse DNS in ActiveCampaign With a Dedicated IP

ActiveCampaign also requires you to establish a reverse DNS record in order to send email campaigns via their API when you have a dedicated IP. They recommend you have a regular list of 10,000 or more contacts. Otherwise, they recommend using their shared IP address.

Official docs on Revrse DNS & Dedicated IPs in ActiveCampaign

Using Reverse DNS in Your App that Sends Email

Reverse DNS is an important factor when setting up an email server, and it can help to ensure that emails sent from php scripts or other applications reach their destination without being marked as spam. It also helps to establish trustworthiness in the eyes of receiving mail servers and provides more information about the sender. Setting up a reverse DNS record is quite simple and will help make sure that your emails are reliable and secure.

So if you’re looking for improved email deliverability, security, and trustworthiness, setting up a Reverse DNS record for your applications when using an email marketing API is really important. Many good emails have been sent to a junk folder because they failed to setup the right DNS. With a proper configuration in place, you can rest assured that your emails will reach their intended destination reliably and securely.

Dig Deeper with Our Email in PHP Examples and Guides


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