How to send emails using Go(golang).
Send emails using the go standard library (net/smtp).
Prerequisites
To follow along, you will need to have golang installed locally
Step 1: Create a project and configure it
Create a project directory, and in that type the following commands.
go mod init send_mail
We are going to use the GoDotEnv package to load the .env file
go get github.com/joho/godotenv
In the root directory create a go file called main.go
package main
import (
"fmt"
"log"
"net/smtp"
"os"
"github.com/joho/godotenv"
)
func main() {
err := godotenv.Load(".env")
if err != nil {
log.Fatalf("Error loading .env file")
}
_, ok := os.LookupEnv("MAIL_USER")
if !ok {
log.Fatalf("SMTP username not set")
}
_, ok = os.LookupEnv("MAIL_PASSWORD")
if !ok {
log.Fatalf("SMTP password not set")
}
_, ok = os.LookupEnv("MAIL_HOST")
if !ok {
log.Fatalf("SMTP host not set")
}
_, ok = os.LookupEnv("MAIL_PORT")
if !ok {
log.Fatalf("SMTP port not set")
}
response := sendMail("walkerbrownmason@outlook.com", "This is a test mail", "Hello walker what are you up to")
fmt.Println(response)
os.Exit(0)
}
This is just a boiler plate to start our project.
Step 2: Create the sendMail function
To send mail using the net/smtp standard library, you first need to authenticate with your smtp server using the smtp.PlainAuth function.
func sendMail(to, subject, body string) Response {
username := os.Getenv("MAIL_USER")
password := os.Getenv("MAIL_PASSWORD")
host := os.Getenv("MAIL_HOST")
port := os.Getenv("MAIL_PORT")
auth := smtp.PlainAuth("", username, password, host)
}
After authenticating with your smtp server, you can now send an email with the smtp.SendMail function. Append the following code to oursendMail function.
err := smtp.SendMail(host+":"+port, auth, username, []string{to}, []byte("Subject: "+subject+"\n"+body))
if err != nil {
log.Fatalf(err.Error())
}
return Response{
status: 200,
message: "Mail sent",
}
The sendMail function now becomes:
func sendMail(to, subject, body string) Response {
username := os.Getenv("MAIL_USER")
password := os.Getenv("MAIL_PASSWORD")
host := os.Getenv("MAIL_HOST")
port := os.Getenv("MAIL_PORT")
auth := smtp.PlainAuth("", username, password, host)
err := smtp.SendMail(host+":"+port, auth, username, []string{to}, []byte("Subject: "+subject+"\n"+body))
if err != nil {
log.Fatalf(err.Error())
}
return Response{
status: 200,
message: "Mail sent",
}
}
Let's now define the Response struct.
type Response struct {
status int
message string
}
Step 3: Run the script using the go run command
go run main.go
You should get a response like
{200 Mail sent}