https://github.com/modfin/smtpx
A lightweight SMTP server package written in Go that feels familiar.
https://github.com/modfin/smtpx
Last synced: about 1 year ago
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A lightweight SMTP server package written in Go that feels familiar.
- Host: GitHub
- URL: https://github.com/modfin/smtpx
- Owner: modfin
- License: mit
- Created: 2025-03-17T13:19:20.000Z (over 1 year ago)
- Default Branch: master
- Last Pushed: 2025-06-13T14:50:21.000Z (about 1 year ago)
- Last Synced: 2025-06-13T15:23:48.304Z (about 1 year ago)
- Language: Go
- Size: 1 MB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# SMTPX
> A lightweight SMTP server package written in Go that feels familiar.
## Installation
```bash
go get github.com/modfin/smtpx
```
## Usage
One idea for smtpx is to have it feel familiar and have the same feel as the standard library has for `net/http`.
```go
package main
import (
"context"
"crypto/tls"
"fmt"
"github.com/modfin/smtpx"
"github.com/modfin/smtpx/envelope"
"github.com/modfin/smtpx/middleware"
"github.com/modfin/smtpx/responses"
"golang.org/x/crypto/acme/autocert"
"log/slog"
"os"
"os/signal"
"time"
)
func main() {
hostname := "example.com"
certManager := &autocert.Manager{
Prompt: autocert.AcceptTOS,
Cache: autocert.DirCache("acme-cache"),
HostPolicy: autocert.HostWhitelist(hostname),
}
slog.SetLogLoggerLevel(slog.LevelDebug)
server := smtpx.Server{
Logger: slog.Default(),
// Hostname is used for HELO command, and is required for TLS
Hostname: hostname,
Addr: ":25",
// TLSConfig is optional and is used for STARTTLS command
TLSConfig: &tls.Config{ // example using autocert for TLS
GetCertificate: certManager.GetCertificate,
},
// Middlewares are executed in order
Middlewares: []smtpx.Middleware{
middleware.Logger(slog.Default()),
middleware.Recover,
middleware.AddReturnPath,
},
// Handler for incoming emails
// smtpx.NewHandler creates a handler from a function
Handler: smtpx.NewHandler(func(e *envelope.Envelope) smtpx.Response {
fmt.Println("Command MAIL", e.MailFrom)
fmt.Println("Command RCPT", e.RcptTo)
fmt.Println("Command DATA", e.Data.String())
// Opening the envelope and getting the mail
// ie. Splitting the Data section of a email into header and body
mail, err := e.Mail()
if err != nil {
return responses.FailSyntaxError
}
// Parses headers while keeping encoding.
// For human-readable decoded format, use mail.Headers()
headers, err := mail.HeadersLiteral()
// Error handling ignored for brevity
fmt.Println("From:", headers.From())
fmt.Println("To:", headers.To())
fmt.Println("Subject:", headers.Get("Subject"))
fmt.Println("Body:", string(mail.Body()))
return smtpx.NewResponse(250, "OK")
}),
}
// Graceful shutdown
go func() {
sig := make(chan os.Signal, 1)
signal.Notify(sig, os.Interrupt, os.Kill)
<-sig
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
err := server.Shutdown(ctx)
if err != nil {
slog.Default().Error("failed to shutdown server", "err", err)
}
}()
if err := server.ListenAndServe(); err != nil {
slog.Default().Error("failed to start server", "err", err)
}
}
```
## Tribute
### A Fork
`smtpx` started out as a fork of `go-guerrilla` but there is very little left from the original project.
The goal is quite different for `smtpx`, and pretty much everything has been rewritten in
a more go-like way focused on have `smtpx` work as a package and not a stand-alone server.
https://github.com/phires/go-guerrilla (original https://github.com/flashmob/go-guerrilla)
### Other projects
There are a few other smtp servers written in go, so please have look before using `smtpx`.
- https://github.com/emersion/go-smtp
- https://github.com/phires/go-guerrilla
- https://github.com/foxcpp/maddy
### License
MIT