smtp

smtp

The extended go src/net/smtp package

Example

package main

import (
  "fmt"
  
  "github.com/rwscode/smtp"
)

var (
  from     = "noreply@example.com"
  to       = []string{"ex1@example.com", "ex2@example.com"}
  host     = "smtp.example.com"
  port     = "587" // 25 for smtp, 587 for STARTTLS, 465 for TLS
  portTLS  = "465" // 25 for smtp, 587 for STARTTLS, 465 for TLS
  username = "mailuser"
  password = "mailpasswd"
  subject  = "Test message"
  message  = `This is a test message by Go rwscode/smtp`
)

func main() {
  err := smtp.Mail().Message(&smtp.Message{
    From:    &smtp.Email{Addr: from},
    To:      to,
    Subject: subject,
    Content: smtp.Content{ContentType: smtp.Plain, Body: message},
  }).PlainAuth(username, password, host).Send(host, port, false)
  if err != nil {
    fmt.Println("send mail error:", err)
    return
  }
  fmt.Println("send mail successful")
}

func mainTLS() {
  err := smtp.Mail().Message(&smtp.Message{
    From:    &smtp.Email{Addr: from},
    To:      to,
    Subject: subject,
    Content: smtp.Content{ContentType: smtp.Plain, Body: message},
  }).PlainAuth(username, password, host).Send(host, portTLS, true)
  if err != nil {
    fmt.Println("send mail error:", err)
    return
  }
  fmt.Println("send mail successful")
}

SMTP transport example

S: 220 smtp.example.com ESMTP Postfix
C: HELO relay.example.org
S: 250 Hello relay.example.org, I am glad to meet you
C: MAIL FROM:<bob@example.org>
S: 250 Ok
C: RCPT TO:<alice@example.com>
S: 250 Ok
C: RCPT TO:<theboss@example.com>
S: 250 Ok
C: DATA
S: 354 End data with <CR><LF>.<CR><LF>
C: From: "Bob Example" <bob@example.org>
C: To: "Alice Example" <alice@example.com>
C: Cc: theboss@example.com
C: Date: Tue, 15 Jan 2008 16:02:43 -0500
C: Subject: Test message
C:
C: Hello Alice.
C: This is a test message with 5 header fields and 4 lines in the message body.
C: Your friend,
C: Bob
C: .
S: 250 Ok: queued as 12345
C: QUIT
S: 221 Bye

SMTP Extensions

• 8BITMIME – 8 bit data transmission, RFC 6152
• ATRN – Authenticated TURN for On-Demand Mail Relay, RFC 2645
• AUTH – Authenticated SMTP, RFC 4954
• CHUNKING – Chunking, RFC 4954
• DSN – Delivery status notification, RFC 3461 (See Variable envelope return path)
• ETRN – Extended version of remote message queue starting command TURN, RFC 1985
• HELP – Supply helpful information, RFC 821
• PIPELINING – Command pipelining, RFC 2920
• SIZE – Message size declaration, RFC 1870
• STARTTLS – Transport Layer Security, RFC 3207
• SMTPUTF8 – Allow UTF-8 encoding in mailbox names and header fields, RFC 6531
• UTF8SMTP – Allow UTF-8 encoding in mailbox names and header fields, RFC 5336 (deprecated[28])