What is reverse DNS (PTR)?
Reverse DNS: the meaning
Where ordinary DNS translates a name into an IP address, reverse DNS does the opposite: from IP address to name. For email that link is stored in a PTR record. Receiving servers use it as one of the checks against spam.
Explanation
If a sending mail server lacks a proper reverse DNS record, many recipients view its mail with suspicion and the chance of a spam label is greater. A correct PTR record that matches the server name contributes to a good reputation. This mainly comes into play at server level; with a hosted service it's usually already taken care of. You can read more in reverse DNS (PTR) for email.
Example
The mail server that sends mail for yourbusiness.be has IP address 203.0.113.10. A receiving server does a reverse lookup, gets a proper server name back via the PTR record that matches the sender, and considers the mail more trustworthy.
Why reverse DNS matters
Large receiving parties are strict about senders they can't place. A missing or incorrect PTR record is, for them, a reason for suspicion, with a greater risk of delay or a spam label. For you as a user it's reassuring that you rarely have to tinker with this yourself: reverse DNS is arranged at server level, and with a professionally hosted service it's usually already set up neatly. If you send from your own server, however, it's something to check.
Related terms
- Reverse DNS (PTR) for email
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