You enter a working address and still get an error. It is not invalid. It is on a list.
How detection works
There are publicly maintained registries listing thousands of domains belonging to temporary address services. Some sit openly on developer platforms, others are sold commercially and updated continuously. A provider includes such a list and compares the part after the @ on every registration.
More elaborate checks go further:
- MX comparison. If the mail servers of several suspect domains point at the same infrastructure, all of them get recognised together.
- Domain age. Registered two weeks ago looks suspicious.
- Recipient verification. The provider asks the mail server whether that specific address exists. With a catch-all the answer is always yes — and that itself is a giveaway.
The lists in question
These directories are no secret. Four of the most widely used sit openly on GitHub:
- disposable-email-domains with around 8,200 entries
- disposable with around 75,000
- mailchecker with around 56,000
- fakefilter with around 10,000
We checked all four on 10 August 2026: getsend.xyz is on none of them. That explains why sign-ups with our addresses still go through in many places. It also shows how little that is worth. A single entry in one of these lists is enough, and every service that uses it will refuse. We are not told, we are not asked, and undoing it means writing to each maintainer separately.
Why providers do it
The reasons are usually reasonable:
- Repeated use of free offers. Unlimited addresses mean unlimited trial accounts.
- No reachability. A shop that cannot reach anyone when there is a problem has a real problem.
- Delivery statistics. Addresses that disappear after days generate bounces — and those damage their own reputation.
- Abuse prevention. For reviews, votes or referral programmes, disposable addresses are the tool of choice.
For banking, government or contracts, rejection is simply correct. A temporary address is unsuitable for those cases anyway — we drew that boundary in detail in a separate post.
Why it hits us particularly hard
A point about our own situation: we currently offer a single domain. Once it is on such a list, the entire service is unusable at that provider — permanently. Services with dozens of rotating domains lose only a fraction in the same situation.
That is a structural weakness, not a matter of programming. We would rather say so openly than pretend it does not exist.
What you can do
- Check whether this is the right use case. For an account you want to keep, the rejection is a useful hint.
- Use an alias address with forwarding. It runs on a normal domain, is rarely detected, and can still be switched off.
- Try plus addressing if your provider supports it. It also gets rejected occasionally, but less often.
- Your own domain. Owning one lets you create as many addresses as you like, none of them on any list.
And if you run a form yourself?
A blanket ban costs you genuine users too. Two gentler routes usually work better: require a confirmation click instead of checking the domain — anyone genuinely using the address will confirm it. And limit the block to the places where it actually hurts, such as free trials, rather than applying it to every newsletter.