Email domain debugger
“The confirmation code never came” usually has one of three causes, and from the sign-up form all three look the same. This page tells them apart in a couple of seconds. Paste the whole address — or just the domain — and it reports:
- whether the address is written in a form that can work at all;
- whether the domain exists, and what its name servers say;
- whether any mail server accepts mail for it, and whether that server is ours;
- whether it is a Gmail form that is really the same mailbox as another one;
- how an international domain looks in the ASCII form that sign-up forms expect.
Reading the answer
| What you see | What it means | What to do |
|---|---|---|
| Green line at the bottom | The domain points here and mail will reach us. | Nothing. If messages still do not arrive, the sender is not sending them. |
| Our server is listed, but not first | A record with a smaller priority number takes all the mail. | Give ours the lowest number, or remove the other records. |
| Two records share the highest priority | The sender picks either one, so mail arrives only some of the time. | Leave a single record at the lowest number. |
| MX records exist, but point elsewhere | The domain is fine; another system simply handles its mail. | If the domain is yours, repoint the record here. |
| No MX record found | Nothing anywhere accepts mail for this domain. | Add a record, or use one of our addresses instead. |
| No name servers found | The domain is not live on the internet at all. | Most often the registration has expired. |
ℹ️
The lookup runs the moment you press the button, against public DNS — there is no queue and no saved verdict from an earlier visit. What comes back is what DNS says right now.
What this cannot tell you
One thing, deliberately: whether a particular website will accept an address at this domain. That is a list on their side, invisible from outside, and no DNS check can see it. So if the domain checks out here and a sign-up form still refuses the address, the domain is fine — the form is the obstacle, and that is a different problem with a different fix.
Next steps
- Use your own domain — the exact MX value to publish, and this page to confirm it took.
- Sending and SMTP — why an address that receives fine still cannot send.
- Domains you can use right away — when you would rather not debug anything at all.