golang net/smtp getting smtp server response DSN - email

Question

I am using golang net/smtp to send mails
Whenever I send to my smtp server I need to capture the response from the server
Especially the DSN
For example my local smtp server gives a "ok queued as " at the end of the mail
I need to capture this and print in the logs
How can I do this
package main
import (
"log"
"net/smtp"
)
func sendEmail(msg []byte) {
c, err := smtp.Dial("localhost:25")
if err != nil {
log.Fatal(err)
}
if err := c.Mail("sender#example.org"); err != nil {
log.Fatal(err)
}
if err := c.Rcpt("recipient#example.net"); err != nil {
log.Fatal(err)
}
wc, err := c.Data()
if err != nil {
log.Fatal(err)
}
_, err = wc.Write(msg)
if err != nil {
log.Fatal(err)
}
//How do I get the response here ??
err = wc.Close()
if err != nil {
log.Fatal(err)
}
err = c.Quit()
if err != nil {
log.Fatal(err)
}
}

Answer 1

As mentioned in the comments you can use c.Text.ReadResponse():
package main
import (
"net/smtp"
)
func sendEmail(msg []byte) (code int, message string, err error) {
c, err := smtp.Dial("localhost:25")
if err != nil {
return
}
defer c.Quit() // make sure to quit the Client
if err = c.Mail("sender#example.org"); err != nil {
return
}
if err = c.Rcpt("recipient#example.net"); err != nil {
return
}
wc, err := c.Data()
if err != nil {
return
}
defer wc.Close() // make sure WriterCloser gets closed
_, err = wc.Write(msg)
if err != nil {
return
}
code, message, err = c.Text.ReadResponse(0)
return
}
The code, message and any err are now passed to the caller, don't use log.Fatal throughout your code, handle the error on the calling side.

Answer 2

package main
import (
"net/smtp"
)
func sendEmail(msg []byte) (code int, message string, err error) {
c, err := smtp.Dial("localhost:25")
if err != nil {
return
}
defer c.Quit() // make sure to quit the Client
if err = c.Mail("sender#example.org"); err != nil {
return
}
if err = c.Rcpt("recipient#example.net"); err != nil {
return
}
wc, err := c.Data()
if err != nil {
return
}
_, err = wc.Write(msg)
if err != nil {
return
}
code, message, err = closeData(c)
if err != nil {
return 0, "", err
}
return code, message, err
}
func closeData(client *smtp.Client) error {
d := &dataCloser{
c: client,
WriteCloser: client.Text.DotWriter(),
}
return d.Close()
}
type dataCloser struct {
c *smtp.Client
io.WriteCloser
}
func (d *dataCloser) Close() (int, string, error) {
d.WriteCloser.Close() // make sure WriterCloser gets closed
code, message, err := d.c.Text.ReadResponse(250)
fmt.Printf("Message %v, Error %v\n", message, err)
return code, message, err
}