ZeroSMTP

Send an email from a GitHub Actions workflow through the free ZeroSMTP relay (mx.msgwing.com) — no paid transactional-email service, no SMTP server to run, and no volume-based pricing tiers. A composite action wrapping curl's built-in SMTP support — no extra runtime or dependency installed on the runner.

Usage

- name: Notify on failure
  if: failure()
  uses: msgwing/send-email-action@v1
  with:
    username: ${{ secrets.ZEROSMTP_USERNAME }}
    password: ${{ secrets.ZEROSMTP_PASSWORD }}
    from: ${{ secrets.ZEROSMTP_USERNAME }}
    to: you@example.com
    subject: "CI failed on ${{ github.repository }}"
    body: "Workflow ${{ github.workflow }} failed: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"

Setup

1. Register a free account at msgwing.com to get SMTP credentials (a random @msgwing.com address + password).
2. Add ZEROSMTP_USERNAME and ZEROSMTP_PASSWORD as repository secrets — never hardcode them in the workflow file.
3. Add the step above to any workflow (build failures, deploy notifications, scheduled reports, etc.).

Inputs

Input	Required	Default	Description
username	yes		ZeroSMTP SMTP username
password	yes		ZeroSMTP SMTP password
from	yes		From address (usually the same as username)
to	yes		Recipient address(es) — comma-separated for multiple
subject	yes		Email subject
body	yes		Plain-text email body
port	no	465	465 (implicit SSL/TLS) or 587 (STARTTLS)

Good to know

• Mail is always sent from a shared @msgwing.com address, never from your own domain — fine for CI/CD notifications, not a fit if the "From" needs to show your own domain. See the FAQ.
• The relay is rate-limited (200 emails/day, 50/hour, 5/minute) to keep deliverability good for everyone — see Sending limits.
• Subject/From/To are stripped of embedded line breaks before use, to prevent header injection if any of those values come from less-trusted input (e.g. a PR title).

License

MIT — see LICENSE.