smtp error: 534 when sending email through gmail in golang app

Question

On my golang app I use this snippet to send email from my gmail account:

func send(body string) {
    from := "myaccount@gmail.com"
    pass := "mysupersecretpasswd"
    to := "whoever@whatever.com"

    msg := "From: " + from + "\n" +
        "To: " + to + "\n" +
        "Subject: Hello there\n\n" +
        body

    err := smtp.SendMail("smtp.gmail.com:587",
        smtp.PlainAuth("", from, pass, "smtp.gmail.com"),
        from, []string{to}, []byte(msg))

    if err != nil {
        log.Printf("smtp error: %s", err)
        return
    }

    log.Print("sent, visit whatever)
}

I get this error instead:

smtp error: 534 5.7.14 <https://accounts.google.com/signin/continue?sarp=1&scc=1&plt=AKgnsbud
5.7.14 lxVDnr-tXOckmxXi0fxExY5BKDRczBpGvMCpGWGF97jAI5DlM2oeGMDcIkvBhKT9rJAVnH
5.7.14 WP7zxssynLtkzMb35et-wxJF2AfeBhMA81QqMh2F8fkQRdf9GidA3swFnjfsUl0Pw6fiMT
5.7.14 b3zvEJyD6WAKEWcuxEGJIBTaqCtfDjipQ58cFJweUiKg1_4AJp0fGpC9ufnjBGWqWVKeW9
5.7.14 QVbUstROYK0SzjWXTTvsvZhhG3RjM> Please log in via your web browser and
5.7.14 then try again.
5.7.14  Learn more at
5.7.14  https://support.google.com/mail/answer/78754 61sm6182123wre.44 - gsmtp

I have installed postfix on my localhost. I have also allowed less secure apps to access my account. I have also tried the same code on my VPS, but it does not send emails either.

So what could be wrong? How can I fix it?

Answer 1

I've copied your gist, replaced from, to and password and it works flawlessly. The only reason why this code is not working is that you are NOT allowing less secure apps in gmail.