Golang : How to parse plain email text and process email header?

Problem :

Your program receive email in plain text and you need to parse email header information. How to that in Golang?

Solution :

First, convert the plain text into proper mail message type( see http://golang.org/pkg/net/mail/#Message ) with mail.ReadMessage() function and then process the email header with the associated methods. See example code below.

 package main

 import (
  "bytes"
  "fmt"
  "net/mail"
 )

 var emailData = `From: Adam <[email protected]>
 To: Eve <[email protected]>
 Subject: Do not eat the apple from that tree!
 Date: Fri, 21 Nov 0000 09:55:06 -0600
 Message-ID: <[email protected]>

 Don't listen to that snake. Don't eat the apple!
 `

 func main() {

  msg, err := mail.ReadMessage(bytes.NewBuffer([]byte(emailData)))

  if err != nil {
 panic(err)
  }

  fmt.Println(msg.Header)

  // --------------

  header := msg.Header

  key := "From"

  address, err := header.AddressList(key)

  if err != nil {
 panic(err)
  }

  fmt.Println(address[0].String())

  // --------------

  key = "To"

  addresses, err := header.AddressList(key)

  if err != nil {
 panic(err)
  }

  fmt.Println(addresses[0].String())

  // --------------

  dateTime, err := header.Date()

  if err != nil {
 panic(err)
  }

  fmt.Println(dateTime.String())

  // --------------

  getSubject := header.Get("Subject")

  fmt.Println(getSubject)

 }

Output :

map[Message-Id:[1234@garden.earth] From:[Adam adam@earth.com] To:[Eve eve@earth.com] Subject:[Do not eat the apple from that tree!] Date:[Fri,

21 Nov 0000 09:55:06 -0600]]

"Adam" adam@earth.com

"Eve" eve@earth.com

0000-11-21 09:55:06 -0600 -0600

Do not eat the apple from that tree!

References :

http://golang.org/pkg/net/mail/#Message

https://www.socketloop.com/references/golang-net-mail-header-type-date-get-and-addresslist-functions-example