smtp.dev

Features

Messages

Messages preserve the original email source while exposing parsed text, HTML, headers, attachments, authentication fields, expiry, and audit details.

Inspection views

The web UI provides text, sanitized HTML, headers, raw RFC 5322 source, MIME structure, attachments, and deliverability audit sections. Remote scripts are stripped from rendered HTML previews.

curl https://stmp.ink/api/messages/1 \
  -H "X-API-KEY: $SMTPDEV_API_KEY"

Authentication and audit

Message records include spf_result, dkim_result, and dmarc_result fields. The audit response groups sender, header, size, HTML, link, and expiry checks by severity.

Source and attachments

Use the raw endpoint for exact source and the attachment endpoint for binary downloads. Message JSON also exposes sourceUrl, downloadUrl, and a derived threadId for API clients.

curl https://stmp.ink/api/messages/1/raw \
  -H "X-API-KEY: $SMTPDEV_API_KEY"

curl https://stmp.ink/api/messages/1/attachments/1 \
  -H "X-API-KEY: $SMTPDEV_API_KEY" \
  --output attachment.bin

Expiry

Set expires_at on a message when a test fixture should be cleaned up earlier than the default retention window.

curl -X PATCH https://stmp.ink/api/messages/1 \
  -H "X-API-KEY: $SMTPDEV_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"expires_at":"2026-08-07T12:00:00Z"}'