Mailosaur

Mailosaur

Mailosaur is an email and SMS testing platform for capturing, inspecting, and analyzing messages during development and CI/CD.

Data Model

• Servers — virtual inboxes identified by an 8-char ID (e.g. knyrbtfl). Each server has a unique catch-all address *@SERVER_ID.mailosaur.net. Any email sent to that domain is captured.
• Messages — emails or SMS captured by a server. Summary includes id, from, to, subject, received date. Full detail adds HTML/text body, links, images, attachments, and SMTP headers.
• Attachments — files on messages, downloadable via the Files API.
• Deliverability Reports — per-message analysis: SPF, DKIM, DMARC, blocklists, content flags, SpamAssassin score.
• Usage — account limits (servers, users, emails, SMS) and 31-day transaction history.

Common Workflows

1. Verify signup email: Create or reuse a server → trigger signup with user@SERVER_ID.mailosaur.net → search messages by sentTo → extract verification link from html.links.
2. Test deliverability: Open the captured message id → run deliverability report → check SPF/DKIM/DMARC pass and SpamAssassin score.
3. CI cleanup: Delete all messages on a server between test runs to avoid stale matches.

Gotchas

• server is required for listing and searching messages. Discover the server id from the server directory before message operations.
• Search bodies: Message search expects a JSON body with criteria—not a bare keyword on the URL line.
• Messages arrive asynchronously — if searching immediately after sending, results may be empty. Client libraries usually retry; automation should briefly poll before declaring a miss.
• Deliverability reports require the message to have been received (not just created/sent via the API).