Observed arrival · 2026-09-06
SMTPBox catches your test emails before they reach customers
An SMTP sandbox and REST API for capturing, inspecting, and automating email tests from development, staging, and CI environments.
Field notes
SMTPBox routes application mail to isolated inboxes rather than its original recipients, using either ordinary SMTP credentials or a REST API. The page shows separate boxes for development, staging, CI tests, and feature branches, plus inspection of rendered HTML, plain text, headers, attachments, links, and raw MIME. Its displayed configuration supports STARTTLS on ports 587 and 2525 and implicit TLS on 465, while the free plan states a limit of 2,500 sandbox emails per month.
Observed signals
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