Mail.cx
Mail.cx provides short-lived inboxes for receiving email in developer workflows.
What Mail.cx is
Mail.cx provides short-lived inboxes for receiving email in developer workflows. Developers, QA teams, and product teams can use it to check account verification messages, transactional email, notification pipelines, and application integrations. A web inbox is available without signup; users can choose a username or have one generated randomly. New messages can appear in the browser through server-sent events. Its REST API supports long-polling, access to parsed or raw email, attachment downloads, and event delivery. API traffic is limited to 10 requests per second per token. Long-polling allows one concurrent wait per token and 10 per address. Mail is automatically deleted after one hour on Free and 72 hours on Pro. Mail.cx only receives email, not sends it. It says connections use TLS and describes hashed password and API-token storage. Its terms caution against relying on the service for critical, sensitive, or business-essential communications.
Good
- Web inbox available without signup
- REST API supports parsed and raw email
- Attachments can be downloaded through the API
- Custom domains can be added using DNS verification
- Real-time events can push mail to the browser
Watch out
- The service does not send email
- Free mail is retained for one hour
- API use is limited to 10 requests per second per token
- Terms warn against relying on it for critical communications
Who it suits
Mail.cx suits developers, QA teams, and product teams checking email flows and application integrations. It is intended for receiving test messages, not sending email or handling critical communications.
Verdict
Mail.cx offers a no-signup web inbox and API tools for short-lived email checks. Its one-hour Free retention and receive-only design make it unsuitable for workflows needing message recovery or email sending.
Plans and prices
From Mail.cx's own pricing page, checked 19 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Free | Free | real-time delivery · public system domains · 1-hour mail retention · no signup · rate-limited web inbox |
| Pro | $9.90 a year | 72-hour retention · up to 100 custom domains · dedicated system domains · up to 100 API keys · 10 requests/second · unlimited web inbox without free-plan limits · $9.9/year |
The facts
Each one read from Mail.cx's own pages, with the date it was checked.
What it does
- Advertising boundary
- The inbox, message-reading view, dashboard and authentication screens do not load advertising scripts, while selected marketing pages may show Google AdSense.checked 19 Oct 2026
- API
- The REST API supports long-polling inboxes, retrieving parsed or raw email, downloading attachments, and server-sent event delivery.checked 29 Sep 2026
- API attachments
- Individual email attachments can be downloaded by zero-based attachment index.checked 19 Oct 2026
- API base
- The REST API uses https://api.mail.cx/v1 and authenticates with an x-api-token header.checked 19 Oct 2026
- API domain management
- API endpoints allow adding, listing and deleting custom domains and checking verification status.checked 19 Oct 2026
- API hold time
- Long-poll requests remain open for a server-fixed maximum of 25 seconds.checked 19 Oct 2026
- API inbox endpoint
- The API supports long-polling inbox retrieval with cursor-based since parameters.checked 19 Oct 2026
- API limits
- The API allows 10 requests per second per token; long-polling is limited to one concurrent wait per token and 10 per address.checked 29 Sep 2026
- API message formats
- Developers can retrieve parsed text, HTML and attachments or download the original .eml stream.checked 19 Oct 2026
- API rate limits
- Pro API tokens are limited to 10 requests per second, one concurrent long-poll per token and ten per address.checked 19 Oct 2026
- API SSE
- The API offers server-sent event endpoints for one address or all owned addresses.checked 19 Oct 2026
- API token management
- Tokens can be created, listed and revoked through API endpoints, with plaintext shown only at creation.checked 19 Oct 2026
- Automatic deletion
- Messages and inbox data are automatically deleted when the applicable retention period ends.checked 19 Oct 2026
- Custom domains
- Pro users can connect up to 100 custom domains using DNS verification.checked 19 Oct 2026
- Custom usernames
- Users may choose their own local part or have one generated randomly.checked 19 Oct 2026
- Dedicated domains
- The Pro plan includes dedicated system domains in addition to public domains.checked 19 Oct 2026
- External associated-domain count
- Check-Mail reports fewer than 100 domains associated with mail.cx and says the newest was added five days earlier when checked.checked 19 Oct 2026
- External classification
- Check-Mail classifies mail.cx as a temporary-email provider and recommends blocking associated domains at signup to prevent abuse.checked 19 Oct 2026
- External detection
- Check-Mail says its API detects and blocks mail.cx domains in real time, including newly appearing domains.checked 19 Oct 2026
- External domain age
- HypeStat reported that the mail.cx domain was created on January 29, 2016 and registered through CentralNic.checked 19 Oct 2026
- External hosting
- HypeStat resolved mail.cx through Cloudflare IP addresses and ASN AS13335.checked 19 Oct 2026
- External HTTPS status
- HypeStat reported that mail.cx supports HTTPS and has a certificate for *.mail.cx.checked 19 Oct 2026
- External technology detection
- HypeStat detected Cloudflare, Google AdSense and HTTP/3 on mail.cx.checked 19 Oct 2026
- External traffic estimate
- HypeStat estimated about 124 daily visitors and 170 daily page impressions for mail.cx.checked 19 Oct 2026
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