What 8,740 Disposable Email Domains Have in Common: A Data Study

Disposable email domains have less in common by name than you would expect and far more in common by infrastructure. Of the 8,740 domains on our blocklist, only 4.9% contain an obvious word like "temp" or "trash". But when we looked up every domain's MX record, 47% of the live ones pointed at just ten mail servers.

That second number is the useful one. It means the cheapest way to catch a throwaway address you have never seen before is often to ask where its mail goes, not what it is called.

This post is the full breakdown: what the list is made of, what happened when we checked every entry in DNS, and what that means if you are trying to block disposable emails at signup.

The data and the method

The dataset is the disposable-domain list our verifier uses, 8,740 entries, one domain per line. It is the same list behind the free disposable email checker. Every entry is unique, lower-case and non-empty.

We did two things with it:

1. Static analysis of the names: top-level domains, how many are subdomains of a shared parent, and how many contain giveaway keywords.
2. A live DNS lookup of every domain's MX record, run early on 2 October 2026 (UTC) with dnspython against public resolvers (1.1.1.1, 8.8.8.8 and 9.9.9.9), with up to three attempts per name. Where a domain had no MX record we also asked for an A record. We did not open any SMTP connections.

The raw results, one row per domain, are saved alongside this post's research files, so every figure below can be recounted.

What the names look like

Most disposable domains look like ordinary domains. That is the first and most important finding, because a lot of homemade signup filters still rely on keyword matching.

Pattern	Domains	Share of 8,740
Contains "mail" anywhere	1,725	19.7%
Contains an obvious throwaway word (temp, trash, spam, fake, throw, burn, minute, disposable, tmp, junk, 10min, guerrilla)	430	4.9%
Contains a digit in the first label	1,522	17.4%
Contains a hyphen	812	9.3%
Internationalised (xn--)	10	0.1%

A filter that blocks anything containing "temp" or "trash" catches fewer than one in twenty. A filter that blocks anything containing "mail" would catch a fifth of them, and also block gmail.com, hotmail.com and every company with "mail" in its name. Neither is a strategy.

Top-level domains

The list spans 252 different top-level domains, but .com dominates.

TLD	Domains	Share
.com	3,011	34.5%
.net	785	9.0%
.org	456	5.2%
.de	224	2.6%
.top	198	2.3%
.ru	173	2.0%
.cc	173	2.0%
.uk	170	1.9%
.us	159	1.8%
.info	154	1.8%

Cheap new TLDs show up (.top, .xyz with 139, .site with 133, .store with 131, .cfd with 124), as do the TLDs Freenom used to give away (.tk 100, .ml 74, .ga 69). But no TLD is disposable by nature. Blocking .top wholesale would block real businesses and still miss two-thirds of the list, which sits on .com, .net and .org.

One in seven is a subdomain of a free service

1,186 entries (13.6%) are subdomains of a shared parent rather than registered domains in their own right. The parents are telling:

Parent	Entries on our list
dynv6.net	338
io.vn	109
fr.nf	77
eu.cc	72
cc.cd	42
edu.pl	41
ccwu.cc	27
loseyourip.com	25
ooguy.com	25
mywire.org	24

Several of these, including dynv6.net, loseyourip.com, ooguy.com, mywire.org, camdvr.org and ddnsfree.com, are free dynamic-DNS services. Creating a name under them costs nothing and takes seconds, which is exactly the economics a throwaway mail service wants. Note the implication for list maintenance: a list that only stores exact domain names has to add each new subdomain one at a time, forever.

What the DNS says

Two-thirds of the list still receives mail; a fifth of it no longer exists. This is the part most people never measure, and it is the reason a disposable list can be both too big and too small at the same time.

MX lookup result	Domains	Share
MX record present	5,937	67.9%
of which a null MX (., meaning "accepts no mail")	132	1.5%
Live MX	5,805	66.4%
Domain does not exist (NXDOMAIN)	1,860	21.3%
Domain exists, no MX record	841	9.6%
Server failure	88	1.0%
Timed out after three attempts	14	0.2%

Two caveats on reading this. A domain with no MX record can still receive mail if it has an A record, because RFC 5321 falls back to the A record; 652 of the domains without an MX did have one. And a domain that does not exist today may be re-registered tomorrow, by a throwaway service or by a legitimate business. That second case is why old entries are a false-positive risk, not just dead weight.

The null MX records are worth a note. Publishing MX 0 . is the RFC 7505 way of saying "this domain never accepts mail". Some throwaway services retire domains this way when they are blocklisted widely enough to be useless.

The infrastructure is concentrated

Of the 5,805 live domains, 47% route mail to just ten servers. This is what disposable domains actually have in common.

Most common primary MX hosts	Domains
email.chatgpt.org.uk	478
email.gravityengine.cc	404
tinyhost.shop	324
mail.wabblywabble.com	298
vietxf.com	281
generator.email	269
mail.casadorock.com	256
emailfake.com	187
smtp.oneb.net	137
route1–3.mx.cloudflare.net	275 (95 + 90 + 90)

Counted strictly by individual host name, the concentration looks like this:

Top N primary MX hosts	Domains covered	Share of live domains
Top 1	478	8.2%
Top 5	1,785	30.7%
Top 10	2,729	47.0%
Top 20	3,441	59.3%
Top 50	4,164	71.7%

There were 1,250 distinct primary MX hosts in total, and 1,056 of them served exactly one domain on the list. So the shape is a long tail of one-off setups behind a short head of industrial operators, each running hundreds of domains through the same server.

A few other things stood out:

• 280 domains use Cloudflare Email Routing, which forwards mail for free. That is a legitimate service used by ordinary businesses, so its MX host is not a disposable signal on its own.
• 88 point at Google and 17 at Microsoft MX hosts. Again, those hosts are useless as a block signal.
• 70 point at domain-parking MX hosts, which usually means the throwaway service has let the domain lapse and a parking company now owns it.
• 904 domains (15.6%) run their MX on their own name, such as mail.example.com for example.com. These are the hardest to catch without a list.

What this means if you are blocking disposable signups

Use a list, check MX hosts as a second signal, and expect both to age. Each technique covers a different part of the problem.

1. Keep the list as the first check. It is instant and has no network cost. It catches the long tail of one-off domains that no pattern will.
2. Add an MX-host check for unknown domains. Look up the domain's MX and compare the host against a small set of known throwaway mail servers. In our data, the top 50 hosts alone cover 71.7% of live disposable domains, so a short list of hosts generalises to domains you have never seen. Exclude shared infrastructure such as Google, Microsoft and Cloudflare Email Routing, or you will block real companies.
3. Treat NXDOMAIN separately. A domain that does not exist cannot receive your mail whatever list it is on. That is an invalid address, not a disposable one, and an MX lookup tells you so directly.
4. Do not rely on keywords or TLDs. The data above shows why: 4.9% coverage for keywords, and no TLD is safe to block outright.
5. Re-check old entries. With a fifth of the list gone from DNS, any of those names can be re-registered by a real business. A periodic re-scan is cheap and reduces false positives.

Limitations

• This is one list. It is ours, refreshed from upstream public sources. Other lists overlap with it but are not identical, and no list is complete.
• One snapshot. DNS was queried once, on 2 October 2026. Disposable domains churn quickly, so the exact counts will drift within weeks.
• MX is not proof of use. A live MX shows a domain can receive mail. It does not show the domain is still being handed out by a throwaway service today.
• Primary MX only. Concentration figures use the lowest-preference MX host per domain. Backup MX hosts were recorded but not counted.
• No SMTP probing. We did not test whether these servers accept arbitrary addresses, though most throwaway services are catch-all by design. If you want the background on that, see what a catch-all domain is.

The short version

• 8,740 domains, 252 TLDs, 34.5% on .com. Only 4.9% have an obvious throwaway word in the name.
• 13.6% are subdomains, largely of free dynamic-DNS services.
• 66.4% had a live MX on 2 October 2026; 21.3% no longer existed at all.
• 47% of live domains route mail through ten servers. Checking MX hosts is the most effective way to catch a throwaway domain that is not on any list yet.

You can test any domain against the current list with the disposable email checker, or browse the list itself on the disposable domains page.

Raw data: download the full dataset as CSV. It is free to reuse with a link back to this page.