Mailgun with Go

Go library for interacting with the Mailgun API.

Installation

If you are using Go Modules make sure you include the /v5 at the end of your import paths

go get github.com/mailgun/mailgun-go/v5

Usage

Send a message

package main
import (
	"context"
	"fmt"
	"log"
	"time"
	"github.com/mailgun/mailgun-go/v5"
)
// 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 Mailgun API keys in your Account Menu, under "API Security":
// (https://app.mailgun.com/settings/api_security)
var apiKey = "MAILGUN_API_KEY"
func main() {
	// Create an instance of the Mailgun Client
	mg := mailgun.NewMailgun(apiKey)
	// When you have an EU domain, you must specify the endpoint:
	// err := mg.SetAPIBase(mailgun.APIBaseEU)
	sender := "sender@example.com"
	subject := "Fancy subject!"
	body := "Hello from Mailgun Go!"
	recipient := "recipient@example.com"
	// The message object allows you to add attachments and Bcc recipients
	message := mailgun.NewMessage(yourDomain, sender, subject, body, recipient)
	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()
	// Send the message with a 10-second timeout
	resp, err := mg.Send(ctx, message)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("ID: %s Resp: %s\n", resp.ID, resp.Message)
}

Get Events

package main
import (
	"context"
	"fmt"
	"time"
	"github.com/mailgun/mailgun-go/v5"
	"github.com/mailgun/mailgun-go/v5/events"
)
func main() {
	// You can find Mailgun API keys in your Account Menu, under "API Security":
	// (https://app.mailgun.com/settings/api_security)
	mg := mailgun.NewMailgun("MAILGUN_API_KEY")
	it := mg.ListEvents("your-domain.com", &mailgun.ListEventOptions{Limit: 100})
	var page []events.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/v5"
	"github.com/mailgun/mailgun-go/v5/events"
)
func main() {
	// You can find Mailgun API keys in your Account Menu, under "API Security":
	// (https://app.mailgun.com/settings/api_security)
	mg := mailgun.NewMailgun("MAILGUN_API_KEY")
	begin := time.Now().Add(time.Second * -3)
	// Very short poll interval
	it := mg.PollEvents("your-domain.com", &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 []events.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/v5"
)
// 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 = "MAILGUN_API_KEY"
func main() {
	// Create an instance of the Validator
	mg := mailgun.NewMailgun("MAILGUN_API_KEY")
	ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
	defer cancel()
	email, err := mg.ValidateEmail(ctx, "recipient@example.com", false)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Risk: %t\n", email.Risk)
}

Webhook Handling

package main
import (
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"github.com/mailgun/mailgun-go/v5"
	"github.com/mailgun/mailgun-go/v5/events"
	"github.com/mailgun/mailgun-go/v5/mtypes"
)
func main() {
	// You can find Mailgun API keys in your Account Menu, under "API Security":
	// (https://app.mailgun.com/settings/api_security)
	mg := mailgun.NewMailgun("MAILGUN_API_KEY")
	mg.SetWebhookSigningKey("WEBHOOK_SIGNING_KEY")
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		var payload mtypes.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 := events.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/v5"
)
// 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 Mailgun API keys in your Account Menu, under "API Security":
// (https://app.mailgun.com/settings/api_security)
var apiKey = "MAILGUN_API_KEY"
func main() {
	// Create an instance of the Mailgun Client
	mg := mailgun.NewMailgun(apiKey)
	sender := "sender@example.com"
	subject := "HTML email!"
	recipient := "recipient@example.com"
	message := mailgun.NewMessage(yourDomain, 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, err := mg.Send(ctx, message)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("ID: %s Resp: %s\n", resp.ID, resp.Message)
}

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/v5"
)
// 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 Mailgun API keys in your Account Menu, under "API Security":
// (https://app.mailgun.com/settings/api_security)
var apiKey = "MAILGUN_API_KEY"
func main() {
	// Create an instance of the Mailgun Client
	mg := mailgun.NewMailgun(apiKey)
	sender := "sender@example.com"
	subject := "Fancy subject!"
	body := ""
	recipient := "recipient@example.com"
	// The message object allows you to add attachments and Bcc recipients
	message := mailgun.NewMessage(yourDomain, 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, err := mg.Send(ctx, message)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("ID: %s Resp: %s\n", resp.ID, resp.Message)
}

The official mailgun documentation includes examples using this library. Go here.

EU Region

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

mg := mailgun.NewMailgun("MAILGUN_API_KEY")
mg.SetAPIBase(mailgun.APIBaseEU)

Major Version Migration Notes

We are trying to keep breaking changes to a minimum, but sometimes they are necessary.

We are guaranteeing that there will be no breaking changes within a major version.

v4 to v5 Migration

List of changes are in Release v5.0.0.

How to migrate

Upgrade to the latest v4 release (v4.23.0) first.
Get rid of all deprecated code usage. We recommend using staticcheck linter SA1019 check for that (or just look for // Deprecated: comments in the code) and follow the recommendations there. This should make the major version bump go more smoothly.
Update your import paths to use /v5 at the end, e.g.
```
import "github.com/mailgun/mailgun-go/v5"
```

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_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.