Golang SDK

Prerequisites

Before getting started, you’ll need to:

Authorize your sending domain
Create and retrieve your SendLayer API key

Installation

Install the SendLayer Go SDK using the go get command:

go get github.com/sendlayer/sendlayer-go

Usage

After the installation completes, you’re ready to start integrating the SDK into your code. The SDK includes modules to send emails, manage webhooks, and retrieve events.

Sending an Email

Create a new .go file or edit an existing one. Import the sendlayer package and initialize the client with your SendLayer API key.

sendEmail.go

package main

import (
	"fmt"
	"log"
	"os"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	// Initialize the email client with your API key
	sl := sendlayer.New("your-api-key")

	// Send an email
	resp, err := sl.Emails.Send(
		"sender@example.com",
		"recipient@example.com",
		"Test Email",
		"This is a test email",
		"",
		nil, nil, nil,
		nil, nil, nil,
	)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Email sent! Message ID:", resp.MessageID)
}

Sending HTML Emails

To send HTML emails, include the HTML content as the fifth parameter in the Send() method.

sendEmail.go

package main

import (
	"fmt"
	"log"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	sl := sendlayer.New("your-api-key")

	// Send an HTML email
	resp, err := sl.Emails.Send(
		"sender@example.com",
		"recipient@example.com",
		"Test Email",
		"Plain text fallback",
		"<html><body><p>This is a test email sent with the <a href=\"https://sendlayer.com\">SendLayer</a> API!</p></body></html>",
		nil, nil, nil,
		nil, nil, nil,
	)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Email sent! Message ID:", resp.MessageID)
}

You can include both text and html parameters to have both plain text and HTML versions of your email message

Sending to Multiple Recipients

You can send emails to multiple recipients including "CC" and "BCC" email addresses using the EmailAddress struct.

sendEmail.go

package main

import (
	"fmt"
	"log"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	sl := sendlayer.New("your-api-key")

	// Send to multiple recipients
	resp, err := sl.Emails.Send(
		sendlayer.EmailAddress{Email: "sender@example.com", Name: "Sender Name"},
		[]sendlayer.EmailAddress{
			{Email: "recipient1@example.com", Name: "Recipient 1"},
			{Email: "recipient2@example.com", Name: "Recipient 2"},
		},
		"Complex Email",
		"This is a test email!",
		"<p>This is a <strong>test email</strong>!</p>",
		[]sendlayer.EmailAddress{{Email: "cc@example.com", Name: "CC Recipient"}},
		[]sendlayer.EmailAddress{{Email: "bcc@example.com", Name: "BCC Recipient"}},
		[]sendlayer.EmailAddress{{Email: "reply@example.com", Name: "Reply To"}},
		nil, nil, nil,
	)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Email sent! Message ID:", resp.MessageID)
}

Each recipient field accepts either a string email address or a slice of EmailAddress structs containing the recipient’s Name and Email.

There are limits to the number of email recipients you can add to a single request. See our rate limiting guide to learn more.

Including Attachments

You can include attachments to your email message by adding the Attachment struct to the email payload.

sendEmail.go

package main

import (
	"fmt"
	"log"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	sl := sendlayer.New("your-api-key")

	// Send email with attachments
	resp, err := sl.Emails.Send(
		sendlayer.EmailAddress{Email: "sender@example.com", Name: "Sender Name"},
		[]sendlayer.EmailAddress{
			{Email: "recipient1@example.com", Name: "Recipient"},
		},
		"Complex Email",
		"Plain text fallback",
		"<p>This is a <strong>test email</strong>!</p>",
		nil, nil, nil,
		[]sendlayer.Attachment{{Path: "path/to/file.pdf", Type: "application/pdf"}},
		nil, nil,
	)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Email sent! Message ID:", resp.MessageID)
}

The maximum email size SendLayer allows is 10MB. This includes both the message as well as attachment files.

Simply replace the Path field with the path to the attachment file you wish to attach and specify the correct Type. SendLayer SDK supports both local and remote file attachments and allows you to add multiple attachment files. See our tutorial to learn more about attaching files to emails.

Email Parameters

Below is a table containing the supported parameters for sending emails in Go using SendLayer SDK.

Parameter	Type	Required	Description
`from`	`string` or `EmailAddress`	Yes	Email address of the sender. Can be a single email string or an `EmailAddress` struct with `Email` and `Name` fields
`to`	`string` or `[]EmailAddress`	Yes	Email address(es) of the recipient(s). Can be a single email string or a slice of `EmailAddress` structs
`subject`	`string`	Yes	Subject line of the email
`text`	`string`	Yes	Plain text version of the email content
`html`	`string`	No	HTML version of the email content
`cc`	`[]EmailAddress`	No	CC email addresses as a slice of `EmailAddress` structs
`bcc`	`[]EmailAddress`	No	BCC email addresses as a slice of `EmailAddress` structs
`replyTo`	`[]EmailAddress`	No	Reply-to email addresses as a slice of `EmailAddress` structs
`attachments`	`[]Attachment`	No	Slice of `Attachment` structs containing file paths and MIME types
`headers`	`map[string]string`	No	Map containing custom headers as key-value pairs
`tags`	`[]string`	No	Slice of strings for tagging emails

Managing Webhooks

With the SendLayer Go SDK, you can create new webhooks, view all webhooks you’ve created, and also delete a specific webhook.

Creating a New Webhook

To create a new webhook, you’ll need to first import the SendLayer package and initialize it with your API key. Then call the Webhooks.Create() method and specify the required parameters. This method requires the url and event parameters.

webhooks.go

package main

import (
	"fmt"
	"log"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	sl := sendlayer.New("your-api-key")

	// Create a webhook
	webhook, err := sl.Webhooks.Create("https://your-domain.com/webhook", "open")
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Webhook created! ID:", webhook.WebhookID)
}

The event parameter is constrained to the following options:

bounce
click
open
unsubscribe
complaint
delivery

Example success response for new webhook:

{
   "NewWebhookID": 23718
}

Getting All Webhooks

To view all the webhooks you’ve created, use the Webhooks.Get() method.

webhooks.go

package main

import (
	"fmt"
	"log"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	sl := sendlayer.New("your-api-key")

	// Get all webhooks
	webhooks, err := sl.Webhooks.Get()
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Webhooks:", webhooks)
}

Here is an example response:

{
  "Webhooks": [
    {
      "WebhookID": "23718",
      "CreatedAt": "2025-04-11 09:43:07",
      "UpdatedAt": "2025-04-11 09:43:07", 
      "Status": "Enabled",
      "WebhookURL": "http://example.com/webhook",
      "Event": "delivered",
      "LastResponseCode": "0",
      "LastResponseBody": "",
      "LastResponseAt": "0000-00-00 00:00:00",
      "LastResponseTryCounter": "0"
    }
  ]
}

Deleting a Webhook

To delete a specific webhook, use the Webhooks.Delete() method. This method accepts one required parameter webhookId that needs to be an integer.

Deleting a webhook cannot be undone. You won’t be able to recover or access your webhook after deleting it.

webhooks.go

package main

import (
	"log"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	sl := sendlayer.New("your-api-key")

	// Delete a webhook
	webhookId := 23718
	err := sl.Webhooks.Delete(webhookId)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Webhook deleted successfully")
}

Webhooks Parameters

The table below contains details about the supported parameters in the Webhooks module.

Parameter	Type	Required	Description
`url`	`string`	Yes	The webhook endpoint URL where events will be sent
`event`	`string`	Yes	The type of event to listen for. Options: bounce, click, open, unsubscribe, complaint, delivery
`webhookId`	`int`	Yes	Unique identifier for the webhook (used in delete operation)

Retrieving Email Events

You can view all events connected to your API key.

Getting All Events

To get started, import the SendLayer package and initialize it with your API key. Then call the Events.Get() method to retrieve all events.

The Events.Get() method retrieves the top 5 events in your account if no filter parameter is specified.

events.go

package main

import (
	"fmt"
	"log"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	sl := sendlayer.New("your-api-key")

	// Get all events
	events, err := sl.Events.Get(nil, nil, "", "", nil, nil)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Total events:", events.TotalRecords)
}

Example response:

{
  "totalRecords": 5,
  "events": [
    {
      "Event": "delivered",
      "LoggedAt": 1746340896,
      "LogLevel": "info",
      "Message": {
        "Headers": {
          "MessageId": "06e4491f-fc5a-49cb-bc57-xxxxxx",
          "From": [["", "sender@example.com"]],
          "ReplyTo": [],
          "To": [["", "recipient@example.com"]],
          "Cc": [],
          "Bcc": []
        },
        "Size": 2004,
        "Transport": "api"
      },
      "Recipient": "recipient@example.com",
      "Reason": "Email has been delivered."
    }
  ]
}

Filtering Events

The Events.Get() method in the SendLayer client accepts some optional parameters. These parameters can be used to filter the API response. Here is an example:

events.go

package main

import (
	"fmt"
	"log"
	"time"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	sl := sendlayer.New("your-api-key")

	// Filter events for the last 4 hours
	end := time.Now()
	start := end.Add(-4 * time.Hour)
	event := "opened"

	events, err := sl.Events.Get(&start, &end, event, "", nil, nil)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Filtered events:", events.TotalRecords)
}

Events Parameters

The table below contains details about the available parameters in the Events module.

Parameter	Type	Required	Description
`startDate`	`*time.Time`	No	Start date for filtering events
`endDate`	`*time.Time`	No	End date for filtering events
`event`	`string`	No	Filter the API request by the type of event. Supported events include: `accepted`, `rejected`, `delivered`, `opened`, `clicked`, `unsubscribed`, `complained`, `failed`
`messageId`	`string`	No	Filter by the email `MessageId`
`startFrom`	`*int`	No	Specify a starting number for the email filter
`retrieveCount`	`*int`	No	This parameter controls the number of event records that’ll be displayed. It defaults to 5 if none is specified

Error Handling

The SDK provides custom error types (SendLayerError, SendLayerAPIError, SendLayerValidationError) for better error handling. You can use type assertions to handle different error types:

package main

import (
	"errors"
	"fmt"
	"log"

	"github.com/sendlayer/sendlayer-go"
)

func main() {
	sl := sendlayer.New("your-api-key")

	resp, err := sl.Emails.Send(
		"sender@example.com",
		"recipient@example.com",
		"Test Email",
		"This is a test email",
		"",
		nil, nil, nil,
		nil, nil, nil,
	)
	if err != nil {
		var apiErr *sendlayer.SendLayerAPIError
		var valErr *sendlayer.SendLayerValidationError
		if errors.As(err, &apiErr) {
			fmt.Printf("API error: %s (Status: %d)\n", apiErr.Message, apiErr.StatusCode)
			return
		}
		if errors.As(err, &valErr) {
			fmt.Printf("Validation error: %s\n", valErr.Error())
			return
		}
		fmt.Printf("Unexpected error: %s\n", err)
		return
	}

	fmt.Println("Email sent! Message ID:", resp.MessageID)
}

Here is an example error response:

Error: Invalid event name - 'opened' is not a valid event name

More Examples

SendLayer Go SDK

View more details and examples on GitHub.

Quick Start

API Reference

SDK Usage

Guides

Releases

Prerequisites

Installation

Usage

Sending an Email

Sending HTML Emails

Sending to Multiple Recipients

Including Attachments

Email Parameters

Managing Webhooks

Creating a New Webhook

Getting All Webhooks

Deleting a Webhook

Webhooks Parameters

Retrieving Email Events

Getting All Events

Filtering Events

Events Parameters

Error Handling

More Examples

SendLayer Go SDK

Quick Start

API Reference

SDK Usage

Guides

Releases

​Prerequisites

​Installation

​Usage

​Sending an Email

​Sending HTML Emails

​Sending to Multiple Recipients

​Including Attachments

​Email Parameters

​Managing Webhooks

​Creating a New Webhook

​Getting All Webhooks

​Deleting a Webhook

​Webhooks Parameters

​Retrieving Email Events

​Getting All Events

​Filtering Events

​Events Parameters

​Error Handling

​More Examples

SendLayer Go SDK

Prerequisites

Installation

Usage

Sending an Email

Sending HTML Emails

Sending to Multiple Recipients

Including Attachments

Email Parameters

Managing Webhooks

Creating a New Webhook

Getting All Webhooks

Deleting a Webhook

Webhooks Parameters

Retrieving Email Events

Getting All Events

Filtering Events

Events Parameters

Error Handling

More Examples