Mail Trap

A development mail catcher (like MailDev or Mailpit) for testing an extension or app that sends mail. In dev mode, an app whose SMTP is off sends its mail here instead of the host's sendmail, and you read it at http://127.0.0.1:8025.

Install · Configure · Use · Integrations · Example

Install

Mail Trap is built into pocketone, for a single app and for every instance under provider: pocker. There's nothing to install: run pocketone serve --dev with SMTP off and it's active.

In your own Go build, register it before the app starts:

app := pocketbase.New()
mailtrap.MustRegister(app)
app.Start()

Under Pocker, add mailtrap.New() to the extensions. The module is github.com/pockethost/pocketone/ext/mailtrap.

Configure

There is no pocketone.yaml section or settings screen. It turns itself on only when both are true:

• the app is in dev mode (serve --dev, or a dev instance under Pocker), and
• the app's SMTP is off (Settings → Mail).

Turn SMTP on, or run without --dev, and it does nothing. Two environment variables move its ports:

Never expose these ports: anyone who can reach them can read the mail.

Use

1. Start the app with --dev. It prints the inbox address once it's active.
2. Make your extension or app send mail: a verification, a password reset, $app.newMailClient(), a bulk mail campaign. Each caught message is also printed as one line in the terminal.
3. Open http://127.0.0.1:8025. The list refreshes every 2 seconds. Click a message to see it as HTML, Text or Raw source. Clear empties the inbox.

It keeps the last 500 messages, in memory only; they're gone when the process exits. If its ports are taken, it still catches mail and prints each message in the terminal.

Integrations

Works with

Building on Mail Trap

• Its hook runs last. It binds OnMailerSend after the app's own hooks, so your onMailerSend hooks still run and can change the message first. When it takes a message it never calls the next handler, so sendmail never runs.
• SMTP for other tools. The SMTP listener accepts any message (and any AUTH), so anything that speaks SMTP can send to it.
• Go API. mailtrap.Default(reason) returns the process-wide trap, starting it on first use. A Trap has Messages(), Clear(), Add(from, to, raw, label) and AddMessage(msg, label), and Handler() serves the inbox. Trap{SMTPAddr, HTTPAddr}.Start(ctx) runs a separate trap, for example in a test.
• Inbox API. GET /api/messages (newest first, without bodies), GET /api/messages/{id}, GET /api/messages/{id}/raw (.eml) and DELETE /api/messages, on the inbox address.

Example

example/main.go runs one app in dev mode with the trap. Run go run ./example serve --dev from this folder, request a password reset for [email protected] (password password) from the dashboard (log in as [email protected] / password), and read the mail at http://127.0.0.1:8025.

// Command example runs one app in dev mode with the dev mail trap: request a password reset for [email protected]
// in the dashboard and read the mail at http://127.0.0.1:8025.
//
//	go run ./example serve --dev
package main

import (
	"log"

	"ganigeorgiev.com/pocketbase/pocketbase"
	"github.com/pockethost/pocketone/ext/devusers"
	"github.com/pockethost/pocketone/ext/mailtrap"
)

func main() {
	app := pocketbase.New()
	devusers.Register(app)
	mailtrap.MustRegister(app)
	if err := app.Start(); err != nil {
		log.Fatal(err)
	}
}

How it works

It's built on PocketBase's own OnMailerSend hook (the same way Mail Relay takes over an instance's mail), so PocketBase is unchanged. It used to live in core (tools/mailer/trap.go); it moved here on 2026-11-13.

License

MIT

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