# Python Smtpd Module

The `smtpd` module included classes for implementing SMTP servers.

**Note: The `smtpd` module is deprecated as of Python 3.6 and was removed in Python 3.12. The recommended replacement is `aiosmtpd`.**

## Importing the Module

```python
import smtpd
import asyncore
```

## Creating a Debugging Server

A common use case for `smtpd` was to run a local debugging server that prints incoming emails to stdout.

### Command Line

```bash
python -m smtpd -n -c DebuggingServer localhost:1025
```

### Programmatic Usage

To create a server programmatically, you would subclass `smtpd.SMTPServer`.

```python
import smtpd
import asyncore

class CustomSMTPServer(smtpd.SMTPServer):
    def process_message(self, peer, mailfrom, rcpttos, data, **kwargs):
        print('Receiving message from:', peer)
        print('Message addressed from:', mailfrom)
        print('Message addressed to  :', rcpttos)
        print('Message length        :', len(data))
        return

server = CustomSMTPServer(('127.0.0.1', 1025), None)

try:
    asyncore.loop()
except KeyboardInterrupt:
    pass
```

[[programming/python/python]]