aiosmtpd | A reimplementation of the Python stdlib smtpdpy based on asyncio | Email library

Alright, since you're using version 1.3.0, you can follow the documentation for Authentication.

A quick way to start is to create an "authenticator function" (can be a method in your handler class, can be standalone) that follows the Authenticator Callback guidelines.

A simple example:

Barring a bug in asyncio, the issue is likely caused by a call to loop.stop() hidden somewhere in the code base. You probably want to remove or disable those, as they are fundamentally incompatible with run_until_complete, as well as with the more modern asyncio.run.

aiosmtpd is SMTP server. SMTP protocol is used to send, relay or forward messages, but you cannot use it to receive messages. You would need to combine your mailbox application with some implementation of IMAP or POP3.

To translate your CustomSMTPServer into something that uses aiosmtpd, you have to define a handler class with a handle_DATA() method that does the same thing as your process_message() method:

In your code, Controller(Sink(), hostname='::0', port=8025) starts an SMTP server that receives messages on port 8025 and throws them away (the Sink() part). That's why the messages don't show up in your inbox -- when you send an email to localhost:8025, it is never actually sent to your inbox.

aiosmtpd is an SMTP server, meaning it will receive messages sent via SMTP and process them somehow. In your code, the Sink() handler does not process incoming email in any way -- it simply throws incoming messages away.

If you want to send email over the Internet to bob@hate.com, then you should contact the SMTP server responsible for the hate.com domain instead of the SMTP server you're running using aiosmtpd. For this task you will not need to run an SMTP server, since there's supposedly already an SMTP server on the internet running for hate.com; instead, you will need an SMTP client component, which is provided in the smtplib module in the Python standard library. Sending email with SMTP is not something that aiosmtpd is involved with in any way, and you should look for how to use smtplib instead.

Further reading: Email § Operation on Wikipedia.

I was close. I figured from the fact that I could connect via telnet, but EHLO hostname would disconnect that the server was trying to require a TLS connection ahead of time.

When I examined swaks --help I found that there was a slightly different option that would probably do what I wanted:

EDIT: The bug has been fixed in aiosmtpd 1.0b1, so an upgrade should resolve the issue.

In aiosmtpd 1.0a4, an uncaught exception in Proxy.handle_DATA (using data as a str instead of bytes) causes the asyncio task to stop, but the exception is never propagated.

If you upgrade to 1.0a5 you'll get the exception printed properly: "Error: (TypeError) cannot use a string pattern on a bytes-like object". The problem is that as of 1.0a5, Proxy in aiosmtpd is designed for use in a Controller subclass that sets decode_data=True on the aiosmtpd.smtp.SMTP object, but by default, decode_data=False which causes the error. (In my opinion Proxy should be changed to work with decode_data=False, so I've opened PR #74.)

Thus, to use Proxy in aiosmtpd 1.0a4 or 1.0a5 you need to copy and use the UTF8Controller subclass from aiosmtpd/tests/test_handlers.py. I've tested the following script with both 1.0a4 and 1.0a5: