On behalf of all the developers, I'm very happy to announce the release of
aiosmtpd 1.0 final.
aiosmtpd is a re-implementation of the stdlib smtpd.py module on top of the
asyncio framework. It is compliant with the relevant RFCs (5321, 2033, etc.)
and supports both SMTP (Simple Mail Transport Protocol) and LMTP (Local Mail
Transport Protocol) out of the box. It provides for running the server both
from Python and the command line, and it is extensible both by subclassing and
by implementing your own "event handlers".
aiosmtpd is compatible with Python 3.4 (though we will probably drop that soon
so we can use the new async/await keywords) through 3.6.