Gmailを使ってメールを送信する方法 【参考】 https://code.google.com/p/go-wiki/wiki/SendingMail - Authenticated SMTP 【IMAP と POP3 の開始方法】 https://support.google.com/mail/troubleshooter/1668960?rd=1#ts=1665018,1665141,2769074

sendGmail.go

package main

import (
        "log"
        "net/smtp"
)

func main() {
        // Set up authentication information.
        auth := smtp.PlainAuth(
                "",
                "<username>", // [email protected]
                "<password>",
                "smtp.gmail.com",
        )
        // Connect to the server, authenticate, set the sender and recipient,
        // and send the email all in one step.
        err := smtp.SendMail(
                "smtp.gmail.com:587",
                auth,
                "送信アドレス", //[email protected]
                []string{"受信アドレス"},
                []byte("This is the email body."),
        )
        if err != nil {
                log.Fatal(err)
        }
}