How to test email and SMS in Go

1. Create a Mailosaur account

If you already have an account, skip to step 2.

To create a new trial account, sign up here.

2. Create a sample project

Install Go

To see if you already have Go installed, open a terminal window and run this command:

go version

If Go is installed, you’ll see a version number. If you see an error instead, then download Go from its official site and install it.

Create a new project

Run each of these commands to create a new project:

mkdir EmailTests
cd EmailTests
go mod init example.com/emailtests

Install the Mailosaur Go library

Run this command to install the Mailosaur Go package:

go get -u github.com/mailosaur/mailosaur-go

3. Send email to your Mailosaur server

Servers allow you to group tests, permissions, and other settings together. Each server has a Server ID, a domain name. You need these values to both send email to Mailosaur, and to set up automated testing.

You also need an API key to use. You can learn more about creating API keys here.

Retrieve your server’s attributes

1. Go to the Servers page in the Mailosaur Dashboard.
2. Click on the name of the server you want to test with.
3. Click on the API tab.
4. Make a note of the Server ID, domain name and API key.

Send an email to your server

If the domain name of your server above was:

example.mailosaur.net

Then you can send an email to it with these steps:

1. Open up an email client and send an email to anything@example.mailosaur.net
2. Go to the Servers page in the Mailosaur Dashboard.
3. Click on the name of the server you sent an email to.
4. Confirm the email is there. Note that some services (like Gmail) may take 10-20 seconds to send a message through.

To learn more, read our guide on sending email to Mailosaur.

4. Find an email for automated testing

Now that you have a sample project, your server’s credentials, and an email to test, then you’re ready to continue.

Create a file named hello_test.go and type or paste in this code sample, replacing the template code with the values from step 3 above:

package emailtests

import (
  "fmt"
  "testing"
  "github.com/mailosaur/mailosaur-go"
)

func TestExample(t *testing.T) {
  // Available in the API tab of a server
  apiKey := "YOUR_API_KEY";
  serverId := "SERVER_ID";
  serverDomain := "SERVER_DOMAIN";

  m := mailosaur.New(apiKey);

  params := &mailosaur.MessageSearchParams {
    Server: serverId,
  }

  criteria := &mailosaur.SearchCriteria {
    SentTo: "anything@" + serverDomain,
  }

  email, err := m.Messages.Get(params, criteria)

  if (err != nil) {
    t.Error(err)
  }

  // If we have an email, print the subject
  fmt.Println("Subject: " + email.Subject)
}

This code connects to Mailosaur and looks for any email that has been sent to the address provided in the search criteria.

Save your changes and run the code:

go test

If everything is set up correctly, you should see the subject line of the last email you sent, printed to screen:

Subject: My example email

Troubleshooting

If you see an error, e.g. ‘No matching messages found in time’:

• Make sure you have set the sent to address correctly in your code.
• Ensure that you have sent an email to the sent to address (check this is visible in the Mailosaur Dashboard).
• Note that by default, the get method will only look for messages that were received by Mailosaur within the last hour. You can override this using the receivedAfter option (see library reference below).

5. Narrowing your search results

Only find messages received after a certain time

By default, searches include messages received in the last hour, but you can customise the search window with the receivedAfter option.

This example shows you how to only include emails received after your test started:

testStart := time.Now()

// Perform the steps that send a message here

message, _ := client.Messages.Get(&MessageSearchParams{
		Server: "SERVER_ID",
    ReceivedAfter: testStart,
}, &SearchCriteria{
		SentTo: "...",
})

Search criteria

As you can see in the examples so far, you can search for the email address or phone number a message was sent to, but you can also search using this criteria too:

6. Start writing tests

Now that you have a working project that fetches an email, you can use this to begin writing tests for various pieces of functionality.

Check out these guides on the most common test cases:

SMS Testing

You can test SMS messages in much the same way as email. Take a look at our guide on testing SMS messages for more information.

Library reference

The Go client library gives you access to several other methods.

Messages

Messages is the collective name given to the email and/or SMS messages that are sent into Mailosaur for testing. The message object contains everything you need to perform in-depth automated testing.

Messages.Get(params, criteria, options)

Waits for a message to be found. Returns as soon as a message matching the specified search criteria is found.

Recommended: This is the most efficient method of looking up a message, therefore we recommend using it wherever possible.

params := &mailosaur.MessageSearchParams {
  Server: "SERVER_ID",
}

criteria := &mailosaur.SearchCriteria {
  SentTo: "something@{SERVER_ID}.mailosaur.net",
}

message, err := m.Messages.Get(params, criteria)

To learn about Server IDs, and what to replace SERVER_ID with, see sending email to Mailosaur.

Parameters

In addition to the server, you can also set the following…

Criteria

// Search all messages received after midnight on a specific date
params := &mailosaur.MessageSearchParams {
  Server: "SERVER_ID",
  ReceivedAfter: time.Date(2020, 1, 5, 0, 0, 0, 0, time.UTC),
}

criteria := &mailosaur.SearchCriteria {
  SentTo: "something@{SERVER_ID}.mailosaur.net",
}

message, err := m.Messages.Get(params, criteria)

Messages.List(params)

Returns a list of your messages in summary form. The summaries are returned sorted by received date, with the most recently-received messages appearing first.

// List the most recent messages
params := &mailosaur.MessageListParams {
  Server: server
}

result, err := m.Messages.List(params)

if (err != nil) {
  // Handle err
}

// Get the most recent message (the first one in the list)
message = result.Items[0]

fmt.Println("Subject: " + message.Subject)

Parameters

• Server The unique identifier for your Mailosaur Server.
• ReceivedAfter Allows you to customise how far back to look for messages.
• Page Used alongside ItemsPerPage to paginate through results. This is zero-based, meaning 0 is the first page of results.
• ItemsPerPage A limit on the number of results to be returned. This can be set between 1 to 1000, with the default being 50.
• Dir Optionally limits results based on the direction (Sent or Received), with the default being Received.

// List all results received after midnight on a specific date 
// Limit results to the first 10 matches only.
params := &mailosaur.MessageListParams {
  Server: server,
  ReceivedAfter: time.Date(2020, 1, 3, 0, 0, 0, 0, time.UTC),
  Page: 0,
  ItemsPerPage: 50,
}

result, err = m.Messages.List(params)

Messages.Search(params, criteria)

Returns a list of messages matching the specified search criteria, in summary form. The messages are returned sorted by received date, with the most recently-received messages appearing first.

params := &mailosaur.MessageListParams {
  Server: server,
}

criteria := &mailosaur.SearchCriteria {
  SentTo: "someone@SERVER_ID.mailosaur.net",
}

result, err := m.Messages.Search(params, criteria)

if (err != nil) {
  // Handle err
}

// Get the most recent match
message := result.Items[0]

fmt.Println("Subject: " + message.Subject)

Parameters

• Server The unique identifier for your Mailosaur Server.
• Timeout If provided, determines how long to wait for a matching result (provided in milliseconds).
• ErrorOnTimeout When set to false, an error will not be throw if timeout is reached (default: true). Note the data type is *bool, therefore you must set this using a variable (e.g. f := false followed by params.ErrorOnTimeout = &f)
• ReceivedAfter Allows you to customise how far back to look for messages.
• Page Used alongside ItemsPerPage to paginate through results. This is zero-based, meaning 0 is the first page of results.
• ItemsPerPage A limit on the number of results to be returned. This can be set between 1 to 1000, with the default being 50.
• Dir Optionally limits results based on the direction (Sent or Received), with the default being Received.

Criteria

• SentFrom The full email address from which the target message was sent.
• SentTo The full email address to which the target message was sent.
• Subject The subject line of the target email.
• Body Search for part of the message body.
• Match If set to ALL (default), then only results that match all specified criteria will be returned. If set to ANY, results that match any of the specified criteria will be returned.

// Search for all messages sent to someone@SERVER_ID.mailosaur.net,
// received after midnight on a specific date. Limit results to
// the first 10 matches only.
params := &mailosaur.MessageListParams {
  Server: server,
  Page: 0,
  ItemsPerPage: 10,
  ReceivedAfter: time.Date(2020, 1, 3, 0, 0, 0, 0, time.UTC),
}

criteria := &mailosaur.SearchCriteria {
  SentTo: "someone@SERVER_ID.mailosaur.net",
}

result, err := m.Messages.Search(params, criteria)

Messages.GetById(id)

Retrieves the detail for a single email message. Must be used in conjunction with either ```List``` or ```Search``` in order to get the unique identifier for the required message. We always recommend using the ```Get``` method instead.

result, err = m.Messages.List(&mailosaur.MessageListParams {
  Server: server,
})

if (err != nil) {
  // Handle err
}

messageId := result.Items[0].Id

message := m.Messages.GetById(messageId)

fmt.Println("Subject: " + message.Subject)

Messages.Delete(id)

Permanently deletes a message. Also deletes any attachments related to the message. This operation cannot be undone.

m.Messages.Delete(messageId)

Messages.DeleteAll(server)

Permanently deletes all messages held by the specified server. Also deletes any attachments related to each message. This operation cannot be undone.

m.Messages.DeleteAll("SERVER_ID")

Messages.Create(server, messageCreateOptions)

Creates a new message that can be sent to a verified email address. This is useful in scenarios where you want an email to trigger a workflow in your product.

options := &mailosaur.MessageCreateOptions {
  To: "verified-address@example.com",
  Send: true,
  Subject: "Request",
  Text: "Please can you give us a call back?",
}

m.Messages.Create("SERVER_ID", options)

Options

• To The email address to which the email will be sent. Must be a verified email address.
• Send If true, email will be sent upon creation.
• Subject The email subject line.
• Text The plain text body of the email.
• Html The HTML body of the email.

Messages.Forward(messageId, messageForwardOptions)

Forwards the specified email to a verified email address.

options := &mailosaur.MessageForwardOptions {
  To: "verified-address@example.com",
  Text: "FYI",
}

m.Messages.Forward("MESSAGE_ID", options)

Options

• To The email address to which the email will be sent. Must be a verified email address.
• Text Any additional HTML content to forward the email with.
• Html Any additional plain text content to forward the email with.

Messages.Reply(messageId, messageReplyOptions)

Sends a reply to the specified email. This is useful for when simulating a user replying to one of your emails.

options := &mailosaur.MessageReplyOptions {
  Text: "FYI",
}

m.Messages.Reply("MESSAGE_ID", options)

Options

• Text Any additional plain text content to include in the reply.
• Html Any additional HTML content to include in the reply.

Servers

Servers contain all the configuration and set up for.

Servers.List()

Returns a list of your virtual servers. Servers are returned sorted in alphabetical order.

result, err := m.Servers.List()

if (err != nil) {
  // Handle err
}

fmt.Println("You have a server called: " + result.Items[0].Name)

Servers.Create(options)

Creates a new virtual server. Only the name property is required to create a new server via the API.

options := &mailosaur.ServerCreateOptions {
  Name: "My email tests",
}

m.Servers.Create(options) 

Servers.Get(id)

Retrieves the detail for a single server. Simply supply the unique identifier for the required server.

server, err := m.Servers.Get("SERVER_ID")

Servers.GetPassword(id)

Retrieves the password, for use with SMTP and POP3, for a single server. Simply supply the unique identifier for the required server.

password, err := m.Servers.GetPassword("SERVER_ID")

Servers.Update(id, server)

Updates a single server.

retrievedServer, err := m.Servers.Get("SERVER_ID")

if (err != nil) {
  // Handle err
}

retrievedServer.Name = "Updated server name"

m.Servers.Update(retrievedServer.Id, retrievedServer);

Servers.Delete(id)

Permanently deletes a server. Also deletes all messages and associated attachments within the server. This operation cannot be undone.

m.Servers.Delete("SERVER_ID")

Servers.GenerateEmailAddress(id)

Utility method to help you generate a random email address for a given server.

emailAddress := m.Servers.GenerateEmailAddress("SERVER_ID")

fmt.Println(emailAddress) // "bgwqj@SERVER_ID.mailosaur.net"

To learn about Server IDs, and what to replace SERVER_ID with, see sending email to Mailosaur.

Files

Files.GetEmail(messageId)

Downloads an EML file representing the specified email. Simply supply the unique identifier for the required email.

Files.GetAttachment(attachmentId)

Downloads a single attachment. Simply supply the unique identifier for the required attachment.

Analysis

Analysis.Spam(messageId)

Perform spam testing on the specified email.

Usage

Usage.Limits()

Retrieve account usage limits. Details the current limits and usage for your account. This endpoint requires authentication with an account-level API key.

Usage.Transactions()

Retrieves the last 31 days of transactional usage. This endpoint requires authentication with an account-level API key.