Contact form mail handler example for go on appengine

To my surprise I did not find a contact form mail handler example for go? I don't feel like making a wheel today, are there examples available?

EDIT: (cut and paste answer)

package bin

import (
    "fmt"
    "net/http"
    netMail "net/mail"
    "appengine"
    "appengine/mail"
)

func contact(w http.ResponseWriter, r *http.Request) {
    c := appengine.NewContext(r)
    name := r.FormValue("name")
    email := r.FormValue("email")
    subject := r.FormValue("subject")
    message := r.FormValue("message")
    msg := &mail.Message{
            Sender:  name + " <...@yourappid.appspotmail.com>",
            To:      []string{"...@..."},
            ReplyTo: email,
            Subject: subject,
            Body:    message,
            Headers: netMail.Header{
                "On-Behalf-Of": []string{email},
            },
    }
    if err := mail.Send(c, msg); err != nil {
        c.Errorf("Couldn't send email: %v", err)
        fmt.Fprint(w, "Mail NOT send! Error")
    }else{
        fmt.Fprint(w, "Mail send.")
    }
}

NOTE:

1. ReplyTo only works in gmail if Sender and To are different.

2. Sender should have admin role in google cloud console or something@yourappid.appspotmail.com.

This is most likely failing because the Sender can only be

• an email of a developer of you app, or
• something@yourappid.appspotmail.com

I suggest that you hard-code the sender's email, and use the On-Behalf-Of header in which you include the original sender's name/email.

Also, WriteString accepts a single string, not a []string slice.

The minimum modifications for your example would be:

…
msg := &mail.Message{
        Sender:  name + " <developer@yourapp.com>",
        To:      []string{"...@gmail.com"},
        Subject: subject,
        Body:    message,
        Headers: netMail.Header{
            "On-Behalf-Of": []string{email},
        },
}
…

Also, you'll need to make sure the user's name doesn't actually contain an email address. That could cause you problems…

The best would be to do as @elithrar suggested and validate your form.