Basic SMTP Client

smtp.go

package main

import (
	"crypto/tls"
	"fmt"
	"log"
	"net"
	"net/smtp"
)

func main() {
	addr := "smtp.server.com:587"
	conn, err := tls.Dial("tcp", addr, &tls.Config{})
	host, _, _ := net.SplitHostPort(addr)
	c, err := smtp.NewClient(conn, host)
	if err != nil {
		log.Fatal(err)
	}

	creds := smtp.PlainAuth("mailgun.net", "postmaster@sanity.mailgun.org", "", "localhost")
	if err := c.Auth(creds); err != nil {
		log.Printf("during auth")
		log.Fatal(err)
	}
	// Set the sender and recipient first
	if err := c.Mail("sanity@mailgun.net"); err != nil {
		log.Printf("during mail")
		log.Fatal(err)
	}
	if err := c.Rcpt("target@polygon.us-east-1.postgun.com"); err != nil {
		log.Printf("during rcpt")
		log.Fatal(err)
	}
	// Send the email body.
	wc, err := c.Data()
	if err != nil {
		log.Printf("during data")
		log.Fatal(err)
	}
	_, err = fmt.Fprintf(wc, "This is the email body")
	if err != nil {
		log.Printf("during data send")
		log.Fatal(err)
	}
	err = wc.Close()
	if err != nil {
		log.Printf("during close")
		log.Fatal(err)
	}
	// Send the QUIT command and close the connection.
	err = c.Quit()
	if err != nil {
		log.Printf("during quit")
		log.Fatal(err)
	}
}