dkim

DKIM (DomainKeys Identified Mail) middleware

This middleware allows the DKIM signing of mails with go-mail using the github.com/emersion/go-msgauth library as basis. In case you are using other middlewares, this should be the last to be applies, since alteration of the message after signing it, the verification will fail.

Example

package main

import (
	"log"

	"github.com/wneessen/go-mail"
	"github.com/wneessen/go-mail-middleware/dkim"
)

const rsaKey = `-----BEGIN RSA PRIVATE KEY-----
MIICX[...]
-----END RSA PRIVATE KEY-----`

func main() {
	// First we need a config for our DKIM signer middleware
	sc, err := dkim.NewConfig("example.com", "mail",
		dkim.WithHeaderFields(mail.HeaderDate.String(),
			mail.HeaderFrom.String(), mail.HeaderTo.String(),
			mail.HeaderSubject.String()),
	)
	if err != nil {
		log.Fatalf("failed to create new config: %s", err)
	}

	// We then create a new middleware based of our RSA key and the config
	// we just created
	mw, err := dkim.NewFromRSAKey([]byte(rsaKey), sc)
	if err != nil {
		log.Fatalf("failed to create new middleware from RSA key: %s", err)
	}

	// Finally we create a new mail.Msg with our middleware assigned
	m := mail.NewMsg(mail.WithMiddleware(mw))
	if err := m.From("[email protected]"); err != nil {
		log.Fatalf("failed to set From address: %s", err)
	}
	if err := m.To("[email protected]"); err != nil {
		log.Fatalf("failed to set To address: %s", err)
	}
	m.Subject("This is my first mail with go-mail!")
	m.SetBodyString(mail.TypeTextPlain, "Do you like this mail? I certainly do!")
	c, err := mail.NewClient("smtp.example.com", mail.WithPort(25),
		mail.WithSMTPAuth(mail.SMTPAuthPlain),
		mail.WithUsername("my_username"), mail.WithPassword("extremely_secret_pass"))
	if err != nil {
		log.Fatalf("failed to create mail client: %s", err)
	}
	if err := c.DialAndSend(m); err != nil {
		log.Fatalf("failed to send mail: %s", err)
	}
}