Getting Started
Create and configure Email Testing inboxes for deterministic delivery tests.
Create a permanent or expiring test inbox, control its SMTP response, and use magic tags or raw .eml uploads for deterministic tests.
Create an inbox
Use Create Inbox for a permanent or hidden inbox, or Create Ephemeral Inbox for an inbox that expires automatically. Omit domain_id to use the shared sandbox domain. The response contains the generated address, domain_id, kind, smtp_response, and expiration information.
The smtp_response option controls the SMTP response when no magic tag is present:
| Value | Behavior |
|---|---|
accept | Accept the message with SMTP 250. |
soft_bounce | Reject with SMTP 450 4.2.1. |
hard_bounce | Reject with SMTP 550 5.2.1. |
complaint | Accept with 250, store the message, and mark it for a complaint report. |
Magic tags
The last +tag suffix of the recipient local part overrides the inbox's smtp_response for that message:
| Tag | Result |
|---|---|
+accept | Accepted (250). |
+bounce or +softbounce | Soft bounce (450 4.2.1). |
+hardbounce | Hard bounce (550 5.2.1). |
+complaint or +compliant | Accepted (250), then marked as a complaint. |
+ooo | Accepted (250), then an out-of-office reply is requested. |
For example, if the dashboard gives you qa@<sandbox-domain>, send to qa+hardbounce@<sandbox-domain> to use the hard-bounce behavior while the base inbox remains unchanged. Keep the actual inbox address in configuration; do not assume a shared sandbox domain.
Raw .eml uploads
Use Upload .eml to capture a raw RFC 5322 message without an SMTP connection. The upload can optionally target a mailbox with mailbox_id; the service parses it, stores the message, and starts analysis and preview work like an SMTP or MX message.