Minimal SMTP client in Go. Handles MX lookup, mail server connection on common ports.
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Latest commit 64c3efa Dec 6, 2016


I needed a way to send email from a Ponzu installation running on all kinds of systems without shelling out. sendmail or postfix et al are not standard on all systems, and I didn't want to force users to add API keys from a third-party just to send something like an account recovery email.


$ go get

package main

import (

func main() {
    msg := email.Message{
        To: "", // do not add < > or name in quotes
        From: "", // do not add < > or name in quotes
        Subject: "A simple email",
        Body: "Plain text email body. HTML not yet supported, but send a PR!",

    err := msg.Send()
    if err != nil {

Under the hood

email looks at a Message's To field, splits the string on the @ symbol and issues an MX lookup to find the mail exchange server(s). Then it iterates over all the possibilities in combination with commonly used SMTP ports for non-SSL clients: 25, 2525, & 587

It stops once it has an active client connected to a mail server and sends the initial information, the message, and then closes the connection.

Currently, this doesn't support any additional headers or To field formatting (the recipient's email must be the only string To takes). Although these would be fairly strightforward to implement, I don't need them yet.. so feel free to contribute anything you find useful.


Be cautious of how often you run this locally or in testing, as it's quite likely your IP will be blocked/blacklisted if it is not already.