Free tool
Domain check
A sign-up form refused your address and did not say why. Paste the domain — we run the same checks it runs, and explain what each answer means.
Paste a whole email address or a URL if that is easier — we take the domain out of it. Nothing is stored.
What a sign-up form is actually checking
The rejection arrives as one sentence — use a different email address. Behind it sit several separate checks, each refusing for its own reason. Here they are, in the order they usually run.
- 01
The domain is in a disposable catalogue
Open lists of temp-mail domains exist, and a form consults them before sending anything. A match is an instant refusal that no amount of domain configuration undoes.
- 02
The domain has nowhere to deliver mail
If a domain declares no mail route, no message can reach it. Some sites check straight away; others accept the address and silently send nothing — the second is worse, because you find out late, once the address is already in use.
- 03
The domain's reputation is spent
A domain carries the reputation its previous holder earned. A blocklisting outlives the change of owner, so a domain bought with history can be refused from day one through nothing you did.
- 04
Nothing is served on the domain
A domain that accepts mail while showing nothing at all at its own address is a rare thing for a real business to own. It is cheap for a filter to check, so filters check.
- 05
Nobody wrote rules for the domain
SPF and DMARC say who may send mail as the domain. They have nothing to do with receiving, but their absence reads as neglect.
Where the data comes from
The disposable catalogue is the open list from the disposable-email-domains project (8,742 domains), released into the public domain. Reputation comes from Spamhaus. Everything else is asked directly of public name servers, exactly as the mail server on the other side would ask it. Neither the domain you type nor the result is stored.
The full account of how to get an address that gets accepted is in the guides.