Mailgun with Go

Go library for interacting with the Mailgun API.

Installation

If you are using Go Modules make sure you include the /v4 at the end of your import paths

$ go get github.com/mailgun/mailgun-go/v4

Usage

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"github.com/mailgun/mailgun-go/v4"
)

// Your available domain names can be found here:
// (https://app.mailgun.com/app/domains)
var yourDomain = "your-domain-name" // e.g. mg.yourcompany.com

// You can find the Private API Key in your Account Menu, under "Settings":
// (https://app.mailgun.com/app/account/security)
var privateAPIKey = "your-private-key"

func main() {
	// Create an instance of the Mailgun Client
	mg := mailgun.NewMailgun(yourDomain, privateAPIKey)
	
	//When you have an EU-domain, you must specify the endpoint:
	//mg.SetAPIBase("https://api.eu.mailgun.net/v3")

	sender := "[email protected]"
	subject := "Fancy subject!"
	body := "Hello from Mailgun Go!"
	recipient := "[email protected]"

	// The message object allows you to add attachments and Bcc recipients
	message := mailgun.NewMessage(sender, subject, body, recipient)

	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()

	// Send the message with a 10-second timeout
	resp, id, err := mg.Send(ctx, message)

	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("ID: %s Resp: %s\n", id, resp)
}

Get Events

package main

import (
	"context"
	"fmt"
	"time"

	"github.com/mailgun/mailgun-go/v4"
	"github.com/mailgun/mailgun-go/v4/events"
)

func main() {
	// You can find the Private API Key in your Account Menu, under "Settings":
	// (https://app.mailgun.com/app/account/security)
	mg := mailgun.NewMailgun("your-domain.com", "your-private-key")

	it := mg.ListEvents(&mailgun.ListEventOptions{Limit: 100})

	var page []mailgun.Event

	// The entire operation should not take longer than 30 seconds
	ctx, cancel := context.WithTimeout(context.Background(), time.Second*30)
	defer cancel()

	// For each page of 100 events
	for it.Next(ctx, &page) {
		for _, e := range page {
			// You can access some fields via the interface
			fmt.Printf("Event: '%s' TimeStamp: '%s'\n", e.GetName(), e.GetTimestamp())

			// and you can act upon each event by type
			switch event := e.(type) {
			case *events.Accepted:
				fmt.Printf("Accepted: auth: %t\n", event.Flags.IsAuthenticated)
			case *events.Delivered:
				fmt.Printf("Delivered transport: %s\n", event.Envelope.Transport)
			case *events.Failed:
				fmt.Printf("Failed reason: %s\n", event.Reason)
			case *events.Clicked:
				fmt.Printf("Clicked GeoLocation: %s\n", event.GeoLocation.Country)
			case *events.Opened:
				fmt.Printf("Opened GeoLocation: %s\n", event.GeoLocation.Country)
			case *events.Rejected:
				fmt.Printf("Rejected reason: %s\n", event.Reject.Reason)
			case *events.Stored:
				fmt.Printf("Stored URL: %s\n", event.Storage.URL)
			case *events.Unsubscribed:
				fmt.Printf("Unsubscribed client OS: %s\n", event.ClientInfo.ClientOS)
			}
		}
	}
}

Event Polling

The mailgun library has built-in support for polling the events api

package main

import (
	"context"
	"log"
	"time"

	"github.com/mailgun/mailgun-go/v4"
)

func main() {
	// You can find the Private API Key in your Account Menu, under "Settings":
	// (https://app.mailgun.com/app/account/security)
	mg := mailgun.NewMailgun("your-domain.com", "your-private-key")

	begin := time.Now().Add(time.Second * -3)

	// Very short poll interval
	it := mg.PollEvents(&mailgun.ListEventOptions{
		// Only events with a timestamp after this date/time will be returned
		Begin: begin,
		// How often we poll the api for new events
		PollInterval: time.Second * 30,
	})

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	// Poll until our email event arrives
	var page []mailgun.Event
	for it.Poll(ctx, &page) {
		for _, e := range page {
			log.Printf("Got an event: %q (%q)", e.GetName(), e.GetID())
			// Do something with event
		}
	}
}

Email Validations

package main

import (
	"context"
	"fmt"
	"time"

	"github.com/mailgun/mailgun-go/v4"
)

// Your plan should include email validations.
// Use your Mailgun API key. You can find the Mailgun API keys in your Account Menu, under "Settings":
// (https://app.mailgun.com/settings/api_security)
var apiKey string = "your-api-key"

func main() {
	// Create an instance of the Validator
	v := mailgun.NewEmailValidator(apiKey)

	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()

	email, err := v.ValidateEmail(ctx, "[email protected]", false)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Valid: %t\n", email.IsValid)
}

Webhook Handling

package main

import (
	"encoding/json"
	"fmt"
	"net/http"
	"os"

	"github.com/mailgun/mailgun-go/v4"
	"github.com/mailgun/mailgun-go/v4/events"
)

func main() {
	// You can find the Private API Key in your Account Menu, under "Settings":
	// (https://app.mailgun.com/app/account/security)
	mg := mailgun.NewMailgun("your-domain.com", "private-api-key")

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {

		var payload mailgun.WebhookPayload
		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
			fmt.Printf("decode JSON error: %s", err)
			w.WriteHeader(http.StatusNotAcceptable)
			return
		}

		verified, err := mg.VerifyWebhookSignature(payload.Signature)
		if err != nil {
			fmt.Printf("verify error: %s\n", err)
			w.WriteHeader(http.StatusNotAcceptable)
			return
		}

		if !verified {
			w.WriteHeader(http.StatusNotAcceptable)
			fmt.Printf("failed verification %+v\n", payload.Signature)
			return
		}

		fmt.Printf("Verified Signature\n")

		// Parse the event provided by the webhook payload
		e, err := mailgun.ParseEvent(payload.EventData)
		if err != nil {
			fmt.Printf("parse event error: %s\n", err)
			return
		}

		switch event := e.(type) {
		case *events.Accepted:
			fmt.Printf("Accepted: auth: %t\n", event.Flags.IsAuthenticated)
		case *events.Delivered:
			fmt.Printf("Delivered transport: %s\n", event.Envelope.Transport)
		}
	})

	fmt.Println("Serve on :9090...")
	if err := http.ListenAndServe(":9090", nil); err != nil {
		fmt.Printf("serve error: %s\n", err)
		os.Exit(1)
	}
}

Sending HTML templates

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"github.com/mailgun/mailgun-go/v4"
)

// Your available domain names can be found here:
// (https://app.mailgun.com/app/domains)
var yourDomain = "your-domain-name" // e.g. mg.yourcompany.com

// You can find the Private API Key in your Account Menu, under "Settings":
// (https://app.mailgun.com/app/account/security)
var privateAPIKey = "your-private-key"

func main() {
	// Create an instance of the Mailgun Client
	mg := mailgun.NewMailgun(yourDomain, privateAPIKey)

	sender := "[email protected]"
	subject := "HTML email!"
	recipient := "[email protected]"

	message := mailgun.NewMessage(sender, subject, "", recipient)
	body := `
<html>
<body>
	<h1>Sending HTML emails with Mailgun</h1>
	<p style="color:blue; font-size:30px;">Hello world</p>
	<p style="font-size:30px;">More examples can be found <a href="https://documentation.mailgun.com/en/latest/api-sending.html#examples">here</a></p>
</body>
</html>
`

	message.SetHTML(body)

	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()

	// Send the message with a 10 second timeout
	resp, id, err := mg.Send(ctx, message)

	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("ID: %s Resp: %s\n", id, resp)
}

Using Templates

Templates enable you to create message templates on your Mailgun account and then populate the data variables at send-time. This allows you to have your layout and design managed on the server and handle the data on the client. The template variables are added as a JSON stringified X-Mailgun-Variables header. For example, if you have a template to send a password reset link, you could do the following:

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"github.com/mailgun/mailgun-go/v4"
)

// Your available domain names can be found here:
// (https://app.mailgun.com/app/domains)
var yourDomain = "your-domain-name" // e.g. mg.yourcompany.com

// You can find the Private API Key in your Account Menu, under "Settings":
// (https://app.mailgun.com/app/account/security)
var privateAPIKey = "your-private-key"

func main() {
	// Create an instance of the Mailgun Client
	mg := mailgun.NewMailgun(yourDomain, privateAPIKey)

	sender := "[email protected]"
	subject := "Fancy subject!"
	body := ""
	recipient := "[email protected]"

	// The message object allows you to add attachments and Bcc recipients
	message := mailgun.NewMessage(sender, subject, body, recipient)
	message.SetTemplate("passwordReset")
	err := message.AddTemplateVariable("passwordResetLink", "some link to your site unique to your user")
	if err != nil {
		log.Fatal(err)
	}

	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()

	// Send the message with a 10-second timeout
	resp, id, err := mg.Send(ctx, message)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("ID: %s Resp: %s\n", id, resp)
}

The official mailgun documentation includes examples using this library. Go here and click on the "Go" button at the top of the page.

EU Region

European customers will need to change the default API Base to access your domains

mg := mailgun.NewMailgun("your-domain.com", "private-api-key")
mg.SetAPIBase(mailgun.APIBaseEU)

Testing

WARNING - running the tests will cost you money!

To run the tests various environment variables must be set. These are:

• MG_DOMAIN is the domain name - this is a value registered in the Mailgun admin interface.
• MG_PUBLIC_API_KEY is the Public Validation API key - you can get this value from the Mailgun security page
• MG_API_KEY is the Private API key - you can get this value from the Mailgun security page
• MG_EMAIL_TO is the email address used in various sending tests.

and finally

• MG_SPEND_MONEY if this value is set the part of the test that use the API to actually send email will be run - be aware this will count on your quota and this will cost you money.

The code is released under a 3-clause BSD license. See the LICENSE file for more information.