Last active
February 2, 2024 17:05
-
-
Save douglasmakey/90753ecf37ac10c25873825097f46300 to your computer and use it in GitHub Desktop.
Golang - send an email with attachments.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
package main | |
import ( | |
"bytes" | |
"encoding/base64" | |
"fmt" | |
"io/ioutil" | |
"mime/multipart" | |
"net/smtp" | |
"os" | |
"path/filepath" | |
) | |
var ( | |
host = os.Getenv("EMAIL_HOST") | |
username = os.Getenv("EMAiL_USERNAME") | |
password = os.Getenv("EMAIL_PASSWORD") | |
portNumber = os.Getenv("EMAIL_PORT") | |
) | |
type Sender struct { | |
auth smtp.Auth | |
} | |
type Message struct { | |
To []string | |
CC []string | |
BCC []string | |
Subject string | |
Body string | |
Attachments map[string][]byte | |
} | |
func New() *Sender { | |
auth := smtp.PlainAuth("", username, password, host) | |
return &Sender{auth} | |
} | |
func (s *Sender) Send(m *Message) error { | |
return smtp.SendMail(fmt.Sprintf("%s:%s", host, portNumber), s.auth, username, m.To, m.ToBytes()) | |
} | |
func NewMessage(s, b string) *Message { | |
return &Message{Subject: s, Body: b, Attachments: make(map[string][]byte)} | |
} | |
func (m *Message) AttachFile(src string) error { | |
b, err := ioutil.ReadFile(src) | |
if err != nil { | |
return err | |
} | |
_, fileName := filepath.Split(src) | |
m.Attachments[fileName] = b | |
return nil | |
} | |
func (m *Message) ToBytes() []byte { | |
buf := bytes.NewBuffer(nil) | |
withAttachments := len(m.Attachments) > 0 | |
buf.WriteString(fmt.Sprintf("Subject: %s\n", m.Subject)) | |
buf.WriteString(fmt.Sprintf("To: %s\n", strings.Join(m.To, ","))) | |
if len(m.CC) > 0 { | |
buf.WriteString(fmt.Sprintf("Cc: %s\n", strings.Join(m.CC, ","))) | |
} | |
if len(m.BCC) > 0 { | |
buf.WriteString(fmt.Sprintf("Bcc: %s\n", strings.Join(m.BCC, ","))) | |
} | |
buf.WriteString("MIME-Version: 1.0\n") | |
writer := multipart.NewWriter(buf) | |
boundary := writer.Boundary() | |
if withAttachments { | |
buf.WriteString(fmt.Sprintf("Content-Type: multipart/mixed; boundary=%s\n", boundary)) | |
buf.WriteString(fmt.Sprintf("--%s\n", boundary)) | |
} else { | |
buf.WriteString("Content-Type: text/plain; charset=utf-8\n") | |
} | |
buf.WriteString(m.Body) | |
if withAttachments { | |
for k, v := range m.Attachments { | |
buf.WriteString(fmt.Sprintf("\n\n--%s\n", boundary)) | |
buf.WriteString(fmt.Sprintf("Content-Type: %s\n", http.DetectContentType(v))) | |
buf.WriteString("Content-Transfer-Encoding: base64\n") | |
buf.WriteString(fmt.Sprintf("Content-Disposition: attachment; filename=%s\n", k)) | |
b := make([]byte, base64.StdEncoding.EncodedLen(len(v))) | |
base64.StdEncoding.Encode(b, v) | |
buf.Write(b) | |
buf.WriteString(fmt.Sprintf("\n--%s", boundary)) | |
} | |
buf.WriteString("--") | |
} | |
return buf.Bytes() | |
} | |
func main() { | |
sender := New() | |
m := NewMessage("Test", "Body message.") | |
m.To = []string{"to@gmail.com"} | |
m.CC = []string{"copy1@gmail.com", "copy2@gmail.com"} | |
m.BCC = []string{"bc@gmail.com"} | |
m.AttachFile("/path/to/file") | |
fmt.Println(sender.Send(m)) | |
} |
Hi @AddyM I made a small change that should help you with that, I tested it and it worked, also you can contact me directly, I will gladly give you a hand.
Hi, @douglasmakey ! I'm getting the same error as the author above. This code results only empty .csv files... :(
H @douglasmakey , Is there any way to include an image in the email body using the GOalng net/smtp
package?
io/ioutils
has deprecated after go 1.16
package main
import (
"bytes"
"encoding/base64"
"fmt"
"mime/multipart"
"net/smtp"
"os"
"path/filepath"
)
var (
host = os.Getenv("EMAIL_HOST")
username = os.Getenv("EMAIL_USERNAME")
password = os.Getenv("EMAIL_PASSWORD")
portNumber = os.Getenv("EMAIL_PORT")
)
type Sender struct {
auth smtp.Auth
}
type Message struct {
To []string
CC []string
BCC []string
Subject string
Body string
Attachments map[string][]byte
}
func New() *Sender {
auth := smtp.PlainAuth("", username, password, host)
return &Sender{auth}
}
func (s *Sender) Send(m *Message) error {
return smtp.SendMail(fmt.Sprintf("%s:%s", host, portNumber), s.auth, username, m.To, m.ToBytes())
}
func NewMessage(s, b string) *Message {
return &Message{Subject: s, Body: b, Attachments: make(map[string][]byte)}
}
func (m *Message) AttachFile(src string) error {
b, err := os.ReadFile(src)
if err != nil {
return err
}
_, fileName := filepath.Split(src)
m.Attachments[fileName] = b
return nil
}
func (m *Message) ToBytes() []byte {
buf := bytes.NewBuffer(nil)
withAttachments := len(m.Attachments) > 0
buf.WriteString(fmt.Sprintf("Subject: %s\n", m.Subject))
buf.WriteString(fmt.Sprintf("To: %s\n", strings.Join(m.To, ",")))
if len(m.CC) > 0 {
buf.WriteString(fmt.Sprintf("Cc: %s\n", strings.Join(m.CC, ",")))
}
if len(m.BCC) > 0 {
buf.WriteString(fmt.Sprintf("Bcc: %s\n", strings.Join(m.BCC, ",")))
}
buf.WriteString("MIME-Version: 1.0\n")
writer := multipart.NewWriter(buf)
boundary := writer.Boundary()
if withAttachments {
buf.WriteString(fmt.Sprintf("Content-Type: multipart/mixed; boundary=%s\n", boundary))
buf.WriteString(fmt.Sprintf("--%s\n", boundary))
} else {
buf.WriteString("Content-Type: text/plain; charset=utf-8\n")
}
buf.WriteString(m.Body)
if withAttachments {
for k, v := range m.Attachments {
buf.WriteString(fmt.Sprintf("\n\n--%s\n", boundary))
buf.WriteString(fmt.Sprintf("Content-Type: %s\n", http.DetectContentType(v)))
buf.WriteString("Content-Transfer-Encoding: base64\n")
buf.WriteString(fmt.Sprintf("Content-Disposition: attachment; filename=%s\n", k))
b := make([]byte, base64.StdEncoding.EncodedLen(len(v)))
base64.StdEncoding.Encode(b, v)
buf.Write(b)
buf.WriteString(fmt.Sprintf("\n--%s", boundary))
}
buf.WriteString("--")
}
return buf.Bytes()
}
func main() {
sender := New()
m := NewMessage("Test", "Body message.")
m.To = []string{"to@gmail.com"}
m.CC = []string{"copy1@gmail.com", "copy2@gmail.com"}
m.BCC = []string{"bc@gmail.com"}
m.AttachFile("/path/to/file")
fmt.Println(sender.Send(m))
}
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
https://github.com/stvoidit/gosmtp
Please try my version based on the example of this code. Due to the specific situation, I have to use my own implementation, because popular solutions for some reason do not work, although I have implemented very basic things and perhaps not in the best way, but it works for me.