Question 1

What is Mail.cx?

Accepted Answer

Mail.cx is an email testing platform for developers. It provides instant on-demand inboxes for receiving emails, testing account verification flows, and integrating email reception into your applications via REST API, WebSocket events, and webhooks.

Question 2

Does Mail.cx have an API?

Accepted Answer

Yes. Mail.cx provides a full REST API for creating mailboxes, retrieving emails, downloading attachments, and managing custom domains, webhooks, and API tokens. Interactive API documentation is available at mail.cx/api/docs.

Question 3

Does Mail.cx support webhooks?

Accepted Answer

Yes. Pro users can configure webhook endpoints to receive real-time HTTP POST notifications when new emails arrive. Webhooks are signed with HMAC-SHA256 for security and include automatic retry with exponential backoff.

Question 4

Can I use a custom domain with Mail.cx?

Accepted Answer

Yes. Pro users can add up to 5 custom domains by configuring a TXT record for verification and an MX record pointing to Mail.cx's SMTP server. Each domain requires creating mailbox accounts to receive emails.

Question 5

Is Mail.cx free?

Accepted Answer

Yes. The Free plan includes instant test inboxes, real-time email receiving, WebSocket notifications, and 7-day retention. No credit card required. The Pro plan at $9/month adds custom domains, webhooks, API tokens, and up to 100,000 mailboxes.

Question 6

How long are emails retained?

Accepted Answer

All emails are automatically deleted after 7 days for both Free and Pro plans. Attachments and raw .eml files are also permanently removed after expiration.

Developer Email Testing Platform

Instant

Private

API-first