Private, free Mailinator alternatives for verification emails

Q: What's a private Mailinator alternative with an API and no signup?

receivemail.dev: one unauthenticated POST /mailboxes returns a random address plus a secret, and only that secret can read the mail. mail.tm works similarly with an address and password.

Mailinator's free inboxes are public and have no API. Private, free alternatives compared — receivemail.dev, mail.tm, Mailsac, MailSlurp, testmail.app and more. Updated 26 October 2026.

Alternatives at a glance

Tool	Cost	Account	Read mail via API	Inbox privacy	Retention
receivemail.dev	Free, no signup; Pro $7/mo	None	Yes, no key needed	Private (per-mailbox secret)	Free 60 min, Pro 24 h
mail.tm	Free, no paid tiers	None (mailbox created via API)	Yes, no key; 8 req/s per IP	Private (password)	Not published
Mailsac	Free 1,500 ops/mo; from $18/mo	For API key / private inbox	Yes, with key	Public without account; 1 private address free	Plan-dependent
MailSlurp	Free: 100 inboxes, 500 emails/mo; from $19.99/mo	Required	Yes, with key	Private	Persistent
Mailosaur	No free plan; 14-day trial, from $20/mo (yearly)	Required	Yes, with key	Private (own server/domain)	Persistent
testmail.app	Free 100 emails/mo; from $9/mo (yearly)	Required	Full API from the $9 plan	Private namespace	Free 1 day
Mailpit	Free, self-hosted	None (you run it)	Yes (REST)	Your own server	Your choice

Checked against each vendor's pricing and docs pages on 26 October 2026. Plans change — confirm on their sites before you commit. Mailpit only catches mail your own app sends to it over SMTP; it can't receive from a third-party service sending to a public address.

Mailinator has been the go-to throwaway inbox for well over a decade. The free version is genuinely useful for a quick manual check: type any name @mailinator.com, open the public inbox, read the email. For automated tests and for anything you'd rather not have strangers see, though, two things get in the way — the free inboxes are public and world-readable, and programmatic/API access plus private domains need Verified Pro (free, on approval) or a paid plan.

receivemail.dev covers the same "read a verification email in a test" job, but every address is private to whoever created it (reads are gated by a per-mailbox secret returned at creation), and API access is the only interface — there's nothing to log into, and the free tier costs nothing.

Side by side

	receivemail.dev	Mailinator Public (free)	Mailinator Verified Pro / Business
Price	Free; Pro $7/mo	Free	Verified Pro $0 on approval; Business $79/mo billed yearly
Signup / account	None	None	Required
Inbox privacy	Private — secret required to read	Public — anyone who guesses the name reads it	Private domain
API to read messages	Yes	No (web UI only)	Yes
Private / custom domain	No (shared domain, unguessable address)	No	Yes (1 on Verified Pro)
Retention	Up to 60 min free, 24 h on Pro	Temporary	Permanent storage (10 MB on Verified Pro)
Send email	No	No	No
Good for	Automated tests, CI, throwaway checks	One-off manual checks	QA teams needing a private shared domain

Mailinator's plan names and prices change — see mailinator.com/pricing for the current numbers.

Why "public inbox" matters in a test

Anyone watching @mailinator.com can see the verification codes your test triggers — and, if your signup flow leaks anything else (names, reset links), that too.
Addresses are guessable, so another user (or a bot) can land on the same inbox you're using and your test reads their message instead of yours.
Some services now block mailinator.com outright at signup because it's so well known.

receivemail.dev hands you a random address on a less-burned domain and only the holder of the creation secret can read it.

When Mailinator is still the right call

You just want to eyeball one email by hand — the public inbox is faster than any API.
Your team wants a private shared domain everyone uses (that's what Verified Pro and Business add).
You need messages to stick around longer than an hour.
You're already invested in Mailinator's rule-based routing / webhooks.

Moving a test over

# was: hit https://api.mailinator.com/... with an API token
resp=$(curl -s -X POST https://receivemail.dev/mailboxes)
addr=$(echo "$resp" | jq -r .address)
secret=$(echo "$resp" | jq -r .secret)

# ... run your signup against $addr ...

curl -s "https://receivemail.dev/mailboxes/$addr/messages" \
  -H "Authorization: Bearer $secret"

Full shell + Playwright walkthrough: the CI testing guide.

Other alternatives people compare

MailSlurp — a full email platform (send + receive, SMTP/IMAP, permanent inboxes). See the MailSlurp comparison.
Mailosaur — paid email and SMS testing for QA teams. See the Mailosaur comparison.
mail.tm / DropMail — also free, no-signup, API-accessible; similar niche to receivemail.dev with different retention and rate limits.

FAQ

Are Mailinator's free inboxes private?

No. On the free Public plan any inbox can be opened by anyone who types its name, and API access isn't included. Private inboxes come with Verified Pro (free, on approval) or the paid Business plan.

What's a private Mailinator alternative with an API and no signup?

receivemail.dev: one unauthenticated POST /mailboxes returns a random address plus a secret, and only that secret can read the mail. mail.tm works similarly with an address and password.

Why do some sites reject Mailinator addresses?

It's one of the best-known disposable domains, so many signup forms block it. A less-known domain is less likely to be blocked, though no disposable domain is guaranteed to pass every filter.