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Mail.cx
What it is
Mail.cx provides short-lived inboxes for receiving email in developer workflows. It is designed for developers, QA teams, and product teams checking account verification, transactional messages, notification pipelines, and application integrations. The service receives mail but does not send it. Users can select an inbox name or generate one randomly, and the web inbox does not require signup. New messages can reach the browser through server-sent events. Its REST API supports long-polling, parsed or raw message retrieval, attachment downloads, and event delivery. API use is limited to 10 requests per second per token; long-polling permits one concurrent wait per token and 10 per address. Free mail is kept for one hour and Pro mail for 72 hours, then deleted. The Free plan is free; Pro is $9.90 a year. The pricing note also lists paid access from $4/mo. Mail.cx says it uses TLS connections and hashed password and API-token storage. Its terms caution that messages are not guaranteed to be retained or recovered.
For and against
For
- Web inbox works without signup
- Supports parsed and raw email retrieval
- Attachments can be downloaded through the API
- Real-time mailbox events reach the browser
Against
- The service receives email but cannot send it
- Free mail is retained for one hour
- Messages may not be retained or recoverable
The verdict
Mail.cx offers temporary receiving inboxes with web and API access for testing email-related workflows. Its short retention and service limitations make it unsuitable for communications that must be kept or recovered.
Who it suits
Mail.cx suits developers, QA teams, and product teams that need temporary inboxes for testing email flows. It is not suited to sending mail or relying on inboxes for critical, sensitive, or business-essential communications.
Plans and prices
Free
real-time delivery · public system domains · 1-hour mail retention · no signup
Read 19 Oct 2026 · mail.cx
Pro
72-hour retention · up to 100 custom domains · dedicated system domains · up to 100 API keys
Read 19 Oct 2026 · mail.cx
On the record
- Advertising boundary
- The inbox, message-reading view, dashboard and authentication screens do not load advertising scripts, while selected marketing pages may show Google AdSense.mail.cx · read 19 Oct 2026
- API
- The REST API supports long-polling inboxes, retrieving parsed or raw email, downloading attachments, and server-sent event delivery.mail.cx · read 29 Sep 2026
- API attachments
- Individual email attachments can be downloaded by zero-based attachment index.mail.cx · read 19 Oct 2026
- API base
- The REST API uses https://api.mail.cx/v1 and authenticates with an x-api-token header.mail.cx · read 19 Oct 2026
- API domain management
- API endpoints allow adding, listing and deleting custom domains and checking verification status.mail.cx · read 19 Oct 2026
- API hold time
- Long-poll requests remain open for a server-fixed maximum of 25 seconds.mail.cx · read 19 Oct 2026
- API inbox endpoint
- The API supports long-polling inbox retrieval with cursor-based since parameters.mail.cx · read 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.mail.cx · read 29 Sep 2026
- API message formats
- Developers can retrieve parsed text, HTML and attachments or download the original .eml stream.mail.cx · read 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.mail.cx · read 19 Oct 2026
- API SSE
- The API offers server-sent event endpoints for one address or all owned addresses.mail.cx · read 19 Oct 2026
- API token management
- Tokens can be created, listed and revoked through API endpoints, with plaintext shown only at creation.mail.cx · read 19 Oct 2026
- Automatic deletion
- Messages and inbox data are automatically deleted when the applicable retention period ends.mail.cx · read 19 Oct 2026
- Custom domains
- Pro users can connect up to 100 custom domains using DNS verification.mail.cx · read 19 Oct 2026
- Custom usernames
- Users may choose their own local part or have one generated randomly.mail.cx · read 19 Oct 2026
- Dedicated domains
- The Pro plan includes dedicated system domains in addition to public domains.mail.cx · read 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.check-mail.org · read 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.check-mail.org · read 19 Oct 2026
