If a sign-up form rejects your temporary address, it is not a glitch. Many websites deliberately refuse disposable email. This guide explains why they do it, how they recognise a temp mail address, and what to use when you want to keep your main inbox private without breaking a site's rules.
Why sites block disposable addresses
Fake accounts. An address that takes seconds to create and needs no identity makes it cheap to register many accounts. Sites that deal with spam, fake reviews or abusive users often raise that cost by refusing disposable addresses.
Free trial abuse. When a trial or welcome offer is tied to an email address, a fresh throwaway address can claim it again and again. Blocking temp mail is a simple way to limit that.
Users they cannot reach. A site may need to send receipts, security alerts or password resets. If the address stops working or anyone can read it, those messages fail or reach the wrong person, and the support burden lands on the site.
How detection works
Lists of known disposable domains. The most common method is checking the part after the @ against a list of domains used by temp mail services. Several such lists are maintained publicly and updated as new domains appear.
MX checks. A site can look up the domain's MX records to see which server receives its mail. If the MX points to a host known to serve temp mail, the address can be flagged even when the domain itself is not on a list. You can see what any domain's MX record says with an MX lookup.
Other signals. Some sites also weigh things like how recently a domain was registered or whether it shows signs of being used only for throwaway addresses. The exact rules differ from site to site and are rarely published.
What actually works
Use your real address where you need the account. If the account matters to you, a block on temp mail is a reasonable request. Your everyday address is the one that will still work when you need a password reset.
Use an address on a domain you own when you want sign-ups kept apart from your main inbox. The domain belongs to you, so the address stays reachable and only you read what arrives. With a catch-all, any name at it receives mail, so you can give each site its own address and see who shares it. That is how custom temp mail works on Free Domain Mail. The address is still subject to each site's rules, like any other.
Use your company's domain for work sign-ups. Forms that ask for a work email expect an address at your organisation's domain. If your company has a domain set aside for this, temp business email explains how to receive at any name on it. Only do this where you are allowed to use the domain.
What not to do
Do not try to get past fraud checks. A block on disposable email is often part of how a site protects itself and its users. Working around it to create extra accounts, dodge a ban or hide who you are is the behaviour the block exists to stop.
Do not use any address, including one on your own domain, to claim the same free trial or offer more than once. That breaks most sites' terms regardless of where the address comes from.
Respect each site's terms. If a service requires a real, long-term address, give it one or choose a different service. Free Domain Mail's acceptable use policy rules out fraud and abuse on its own addresses too.
Common mistakes to avoid
- Assuming a rejected address means the site is broken, then cycling through temp mail domains instead of reading the site's sign-up requirements.
- Creating an account you care about with a disposable address that will not receive the password reset later.
- Using a company domain for sign-ups without permission from whoever manages it.
Frequently asked questions
Why is temp mail not working on a site?
Most likely the site checks new addresses against a list of disposable domains, or looks up the domain's MX record and recognises a temp mail host. Some sites may also delay or filter mail to these domains, so the email never shows up. If you need the account, sign up with an address you control.
Is it legal for websites to block temp mail?
Generally, yes. A website can decide which email addresses it accepts for its own accounts, in the same way it sets its other sign-up rules.
Will a site block an address on my own domain?
Possibly. Each site decides what to block, and a domain whose mail is handled by a shared receiving host can still be flagged. If a site asks for a specific kind of address, use the one it asks for and follow its terms.
Is using temp mail on a site that blocks it against the rules?
If the site's terms require a real, reachable address, deliberately getting around its check is likely to break them. Read the terms, and use your own address when the site asks for one.