PostRider

PostRider is a self-hosted mail relay. It takes outbound mail over an HTTP API and SMTP submission and delivers it direct to MX with DKIM; it takes inbound mail on MX for the domains an account registers; and it reports what happened to each message through webhooks.

For anyone who wants deliverability without renting it: transactional mail a recipient is already expecting, apps that would rather run their own relay than integrate a SaaS sending provider, teams done paying rent on a problem they mostly don't have.

PostRider handles:

• outbound mail over an HTTP API and SMTP submission, signed with DKIM and delivered direct to MX
• inbound mail on MX for the mailboxes, or the catch-all, of the domains you register
• forwarding from a mailbox to another address, ARC-sealed with the relay's own key, for approved and authenticated senders
• webhooks for inbound mail and delivery events, signed per webhook
• its own TLS certificate, issued and renewed over ACME
• no reputation score, no warm-up schedule, no pricing tier

Ship the email. Trust that the people who want it will find it.

Contents

• Deliverability Is Overrated
• Why Run Your Own?
• Ship the Email
• Installation
• API (HTTP & SMTP sending)
• Webhooks
• Statuses & Lifecycle
• Development
• Deployment & Operations
• History
• Contributing
• License

Deliverability Is Overrated

Not the concept. The panic.

Somewhere along the way, "send an email" became a SaaS category. Dashboards. Reputation scores. Warm-up schedules. Pricing tiers built around inbox placement. All of it makes sense if you're blasting newsletters at people who never asked. Most email isn't that. Most email is something a person is actually waiting for.

Take the clearest case: a password reset, sent to someone who signed up ninety seconds ago and is staring at their inbox right now. That person isn't a cold prospect. They're mid-task. They triggered the email. They want the email. If it's not in the inbox, they'll check spam without a second thought. The context does the deliverability work for you — you just have to stop getting in its way. And the same holds, to varying degrees, for most of the mail you send: notifications, receipts, updates, the message that lands because someone was expecting it.

So PostRider is a bet: run your own relay, keep it clean, do the fundamentals, and stop paying rent on a problem you mostly don't have. In real use, the bet holds. Mail lands.

Outlook is still Outlook and occasionally has opinions. So do the people you're paying to avoid it.

Why Run Your Own?

Because you can. That used to be reason enough. It still is.

Ship the Email

Ship the email. Trust that the people who want it will find it. Then go spend your engineering time on your actual product instead of babysitting a sender score.

History

View the changelog.

Contributing

See CONTRIBUTING. To report a vulnerability, see SECURITY.

License

MIT. See MIT-LICENSE.