Performing a reverse DNS (rDNS) lookup, also known as a PTR record lookup, is crucial for verifying the authenticity of email servers and ensuring good email deliverability. The `dig -x IP.address.goes.here` command is a common method for conducting a reverse DNS lookup, though online tools and `nslookup` can also be used. The result will provide a hostname, which represents the reverse DNS of that IP address. The PTR record maps an IP address to a domain name, confirming that the IP address is authorized to send emails for the domain and helping prevent email spoofing. A properly configured rDNS record is vital, as many ISPs and email providers use it to verify the authenticity of sending servers and helps fight spam. For optimal deliverability, the reverse DNS should resolve to the same Fully Qualified Domain Name (FQDN) as the sending server, and the PTR record should match your sending domain's reputation; inconsistencies can negatively impact your sender reputation. A missing or incorrect rDNS record can severely impact email deliverability.
8 marketer opinions
Performing a reverse DNS (rDNS) lookup involves identifying the domain name associated with a specific IP address. This process is crucial for verifying the authenticity of email servers and improving email deliverability. Several tools, including online lookup services, and command-line utilities like `dig` or `nslookup`, can be used to perform this lookup. The resulting PTR record should match the sending domain's fully qualified domain name (FQDN). A properly configured rDNS record confirms that the IP address is authorized to send emails for the domain, increasing sender trustworthiness and helping to prevent email spoofing. Conversely, a missing or incorrect rDNS record can significantly harm email deliverability, as major email providers often use it as a spam-filtering criterion. Consistency between the rDNS record and the sending domain's reputation is essential for passing spam filters.
Marketer view
Marketer from Email Geeks shares a tool for looking up reverse DNS records, linking to `xnnd.com`.
27 Feb 2025 - Email Geeks
Marketer view
Email marketer from StackOverflow shares that your server should have a fully qualified domain name (FQDN) and the reverse DNS should resolve to that same FQDN. This consistency is a key factor in passing spam filters.
20 Nov 2021 - StackOverflow
4 expert opinions
Performing a reverse DNS (rDNS) lookup, also known as a PTR record lookup, is crucial for verifying the authenticity of email servers and ensuring good email deliverability. The `dig -x IP.address.goes.here` command is a common method for conducting a reverse DNS lookup. The result will provide a hostname, which represents the reverse DNS of that IP address. A properly configured rDNS record is vital as many ISPs and email providers use it to verify the authenticity of sending servers. For optimal deliverability, ensure the PTR record matches your sending domain's reputation; inconsistencies can negatively impact your sender reputation.
Expert view
Expert from Email Geeks shares the command `dig -x IP.address.goes.here` to perform a reverse DNS lookup.
20 Jul 2021 - Email Geeks
Expert view
Expert from SpamResource.com explains that a properly configured reverse DNS record is vital for email deliverability. Many ISPs and email providers use reverse DNS to verify the authenticity of sending servers.
25 Aug 2021 - SpamResource.com
5 technical articles
Reverse DNS lookups, facilitated by PTR records, map IP addresses to domain names, which is the inverse of a standard DNS A record. The `dig` command with the `-x` option or the `nslookup` command can be used to perform these lookups. The PTR record acts as a pointer to a canonical name, which in the context of reverse DNS, is the domain name associated with the IP address. This process helps verify the legitimacy of the server sending the email and is used as a spam-fighting technique, contributing to email deliverability and server identification.
Technical article
Documentation from Microsoft explains how to verify a reverse lookup zone and its resource records by using the `nslookup` command. The command will return the name associated with the IP address if the PTR record is configured correctly.
29 Sep 2021 - Microsoft
Technical article
Documentation from RFC 1035 describes the PTR record as a pointer to a canonical name. In the context of reverse DNS, this canonical name is the domain name associated with an IP address.
3 May 2024 - IETF
Do PTR records and HELOs impact email deliverability?
How can I determine the ISP or mailbox provider of an email address?
How do I check if the sending IP address matches the IP address of the hostname specified in the Pointer (PTR) record?
How do I configure reverse DNS (rDNS) with multiple IP addresses for email sending?
How does a full circle reverse DNS check work?
What does it mean when a soft bounce reason is 'blocked using Spamhaus' and the IP isn't listed?
What is reverse DNS (rDNS) and FCrDNS, and how do they impact email sending?
Why is reverse DNS important for avoiding spam filters?