如何通过 G-suite 从 Google Cloud 发送电子邮件

Question

How can you send an email in Go from the Google Cloud owner G-suite email account?

Is it possible to use the Google Cloud projectID existing authorizations, without specifying the Google account password inside the Go source files?

Answer 1

I found the solution!

And it's very simple: instead of specifying the account password, you can restrict the connection to your server IP address .

1) Sign in to your Google Admin console ( https://admin.google.com ) using the G-suite administrator account

2) Click on Apps -> G Suite -> Gmail -> Advanced settings

3) At the bottom of the page, mouse over on SMTP Relay Service and click on " ADD ANOTHER "

4) As Allowed Sender select " Only addresses in my domain "

5) Check Only accept mail from the specified IP addresses and type your server IP address

6) Confirm by clicking on " ADD SETTING " and then " SAVE "

This is the Go code required to send an email:

from := "myuser@mydomain.com"
to := "mail@recipient.com"

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

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

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

Answer 2

An even better way is to create API/OAuth2 credentials directly in Google Cloud. In this way you don't even have to specify the server IP addresses as a security measure:

https://medium.com/wesionary-team/sending-emails-with-go-golang-using-smtp-gmail-and-oauth2-185ee12ab306