Which mail servers disposable email domains run on

How many disposable domains can receive mail?#

About three in ten. The rest are dead entries: domains that expired, were never registered under that name, or point nowhere.

The larger run behind StormDoor’s reference data, on a slightly older 61,733-domain version, gave a similar split: 27.5% with MX, 59.1% not existing, 11.4% with no MX [4]. For a signup form this means that a list-only check is checking mostly domains nobody can use; the email.domain_not_found, email.no_mx and email.null_mx checks already reject those on their own.

Which MX hosts do live disposable domains use?#

Each domain is counted once, under its lowest-preference (primary) MX host. “Shared” means the host matches StormDoor’s list of shared providers: ordinary domains use these too, so they say little about disposability. “Other” means it is not on that list.

Counted by provider instead of host, Cloudflare Email Routing (mx.cloudflare.net) is third with 25 domains, because Cloudflare spreads its customers across route1, route2 and route3. Google has 17 and Microsoft (outlook.com) 9.

How concentrated is it?#

Concentration is moderate. No single host carries more than 6% of working domains, but 26 non-shared hosts each serve three or more sampled domains and together carry 257 of the 595. This is the pattern email.disposable_infrastructure relies on: an operator that points many throwaway domains at one server leaves that server in every domain’s public MX record. See how that check performs on unseen domains.

Which of these are legitimate shared providers?#

Two groups appear, and they should be treated differently.

Shared providers used by ordinary domains. In the top 20 these are Google, Cloudflare Email Routing, Namecheap-style registrar forwarding (registrar-servers.com), a parking service (above.com) and a hosting provider (hostedmxserver.com). Domains on them can be disposable (someone pointed a throwaway domain at a forwarding service), but flagging the host would flag every honest customer. StormDoor excludes these from its mail-server matching on purpose. A throwaway domain on Google Workspace is invisible to this method.

Hosts that are not shared providers. The other 14 hosts in the top 20 each appear to serve many domains from the list and are not on StormDoor’s shared-provider list. Some are named after the service itself (mailinator.com, emailfake.com, generator.email). We did not check who operates each host, so “dedicated disposable infrastructure” is our inference from the data, not a verified fact. The signal is that the host serves several listed domains and is not a general-purpose provider.

What should you do with this?#

Check the domain’s MX before accepting an address: seven in ten listed domains cannot receive mail, so MX failure is a strong, cheap signal. For the live remainder, compare MX hosts with hosts already seen serving throwaway domains, and skip shared providers. The MX lookup tool shows any domain’s records. For the difference between checking a domain and confirming a mailbox exists, see email validation vs verification. StormDoor makes the MX lookup tool and the /v1/emails gate. Other vendors’ detection services are compared in best disposable email detection APIs. Domain age is the other cheap signal; see how old disposable domains are.