Português
English
An ordinary DNS record answers the question “what address does this name have?”. The PTR record answers the opposite: “what name does this address have?”. That is why it is called reverse DNS.
It sounds like a networking detail with no consequences. It is not: it is one of the first things a mail server checks before deciding whether to accept your message.
Why e-mail depends on it
When your server delivers a message, the recipient’s server sees the IP connecting and asks the reverse question: who are you?
|
|
| This is why “the e-mail sends but never arrives”. Without a PTR, the message can be refused silently. On your side it looks sent; on theirs it never existed. It is one of the most frequent causes of that symptom. |
Does your service already have one?
| Service | Situation |
| Shared hosting | Already configured. The server’s reverse DNS is ours and it is done — there is nothing for you to do |
| Reseller | Same: the reseller server has its PTR configured |
| VPS or dedicated | The IP is yours, and the PTR is set to whichever name you choose. Ask us and we will handle it |
| The name should make sense. The convention is to point the PTR at the same name the mail server announces — usually something like mail.yourdomain.ao. A PTR pointing at an unrelated name is worth almost as little as having none. |
How to check, in seconds
You need nothing installed — you can do it on your own computer:
| System | Command |
| Windows | nslookup 203.0.113.10 in Command Prompt |
| macOS or Linux | host 203.0.113.10 in Terminal |
| No commands | MXToolbox has a Reverse Lookup option that does the same in the browser |
Replace 203.0.113.10 with the IP you want to test. If a name comes back, the PTR exists. If nothing comes back, it does not — and that is when you act.
A rule that catches people out
With ordinary records, several names can point at the same IP — that is how dozens of sites live on one server. With PTR it is the reverse: one IP has one name, and only one.
So it makes no sense to ask for a PTR “for each domain” on your server. You pick one name, the server’s, and that one answers for all of them.
A PTR on its own is not enough
It is one of three pillars, not the only one. The other two are authentication — SPF, DKIM and DMARC — and sending behaviour. A server with a perfect PTR and no SPF still lands in spam.
And if the IP is already on a blocklist, the PTR will not get it off: see your server IP on a blocklist.
|
Have a VPS and want reverse DNS configured? Tell us the name you want. Request configuration |
RECOMMENDED PRODUCT Professional e-mail on your domain Mailboxes in your company name, no adverts, with spam filtering. from $9.99/mo See plans |
- 0 Users Found This Useful
