Updated · Volt Ghost team
Two ways of refusing mail
| MX answer | Listed domains | Standard? |
|---|---|---|
Null MX (0 .) | 132 | Yes, RFC 7505 (2015) |
localhost | 19 | No, a convention |
localhost. under a lortemail.dk name | 3 | No |
A sender that honours RFC 7505 stops immediately on a null MX and bounces with "556 5.1.10 recipient address has null MX". An MX at localhost does not stop anything: a misconfigured sender may try to deliver to itself. Both mean the same thing for a sign-up form, though: the address cannot receive a code. The 22 localhost names are almost all from 2018 (21), 11 sit on Sedo parking nameservers, and 8 also point their A record at 127.0.0.1.
Parked for sale: the Afternic pattern
| Nameservers | Null MX domains |
|---|---|
ns1/ns2.afternic.com | 121 |
cashparking.com | 3 |
gofruits.co | 3 |
| Any other | 5 |
Afternic is GoDaddy's domain aftermarket. A name on its nameservers is typically listed for sale with a landing page, and the zone it serves is uniform: an A record (102 of them on 76.223.54.146 and 19 on 13.248.169.48, both Amazon addresses), a null MX, and an SPF record of exactly v=spf1 -all (127 of 132). M3AAWG's best practice for parked domains recommends that pairing: refuse inbound mail and declare that nothing is sent. Only 3 of the 132 publish a real DMARC policy; at most of the rest the _dmarc name answers with the same SPF text, a wildcard TXT record rather than a DMARC policy. For parking that still accepts and forwards mail, compare Above.com parking MX.
Where they came from
| Date added | Upstream change | Null MX now |
|---|---|---|
| 8 October 2018 | use neutral language for naming and describing assets in this repo (7448bb6) | 95 of 2,828 |
| 25 February 2025 | add domains from `tempmail io` (#564) (73dc1bd) | 4 of 28 |
| 24 May 2019 | Add additional domains from linshiyouxiang.net (de9e32b) | 3 of 11 |
| 6 August 2023 | Add fakermail.com domains (#399) (9ce2a18) | 2 of 15 |
| 24 February 2024 | more temp-mail.org domains (#445) (7b960ea) | 2 of 24 |
96 of the 132 null MX names were first listed in 2018, 95 in the seed commit of 8 October 2018. They are the temp mail domains of the 2010s: the service closed or moved on, the name expired or was sold, and it ended up in a marketplace inventory. 15 were listed in 2025, including 4 from a tempmail.io batch. 90 of the 132 are .com, the ending aftermarkets trade most.
Will they stay this way?
Most will until someone buys them. Between 5 and 8 Nov 2026, 1 null MX domain switched to a real mail server, 1 domain without MX switched to a null MX, and 1 dead name came back with a localhost MX. A null MX is a property of today's owner, not of the name, which is why the disposable flag stays.
What it means for you
If you run sign-ups, an address at one of these domains is undeliverable: the optional MX check in our email address validator reports a null MX directly, before you need any list. If you are the person signing up and simply need a code to arrive, a parked domain is the wrong tool; a working inbox such as 7-day temp mail receives the message and keeps it for a week. And if you are comparing short-lived inbox services, Volt Ghost vs 10MinuteMail covers how long each one keeps mail.
Other DNS states on the list: gone entirely (NXDOMAIN) and no MX record at all.
Check one domain
Enter one domain and choose MX records: a null MX shows up as a single record pointing at a dot. Or check whether the name is on the disposable list.
Questions
What is a null MX record?
An MX record with preference 0 and a single dot as the host, written 0 . in zone files. RFC 7505 defines it as a statement that the domain accepts no email. Senders should not try to deliver and should fail the message at once with reply code 556 and status 5.1.10.
How many disposable domains publish a null MX?
132 of the 9,894 in our list copy on 8 November 2026. Another 22 point their MX at localhost, which no outside sender can reach either.
Why would a temp mail domain publish a null MX?
Because it is no longer a temp mail domain. 121 of the 132 use Afternic nameservers, the setup a domain marketplace applies to a parked name, and 96 were first listed in 2018. The new owner or the marketplace switched mail off.
Can someone sign up with an address at a null MX domain?
They can type it, but no verification email will ever arrive. Treat it as undeliverable. It stays on the disposable list because a buyer could point the MX somewhere else tomorrow.
