aiosmtplib 1.0.0

asyncio SMTP client

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Introduction

aiosmtplib is an SMTP client for use with asyncio.

Basic usage:

import asyncio
import aiosmtplib

loop = asyncio.get_event_loop()
smtp = aiosmtplib.SMTP(hostname='localhost', port=1025, loop=loop)
loop.run_until_complete(smtp.connect())

async def send_a_message():
    sender = 'root@localhost'
    recipient = 'somebody@localhost'
    message = "Hello World"
    await smtp.sendmail(sender, [recipient], message)

loop.run_until_complete(send_a_message())

Requirements

Python 3.5+, compiled with SSL support, is required.

Connecting to an SMTP server

Initialize a new aiosmtplib.SMTP instance, then run its connect coroutine. Unlike in smtplib, initializing an instance does not automatically connect to the server, as that is a blocking operation.

Sending messages

Use SMTP.sendmail to send raw messages. Allowed arguments are:

sender

The address sending this mail.

recipients

A list of addresses to send this mail to. A bare string will be treated as a list with 1 address.

message

The message string to send.

mail_options

List of options (such as ESMTP 8bitmime) for the mail command.

rcpt_options

List of options (such as DSN commands) for all the rcpt commands.

Use SMTP.send_message to send email.message.Message objects.

Timeouts

All commands accept a timeout keyword argument of a numerical value in seconds. This value is used for all socket operations, and will raise STMPTimeoutError if exceeded. Timeout values passed to init or connect will be used as the default value for commands executed on the connection.

The default timeout is 60 seconds.

Parallel execution

SMTP is a sequential protocol. Multiple commands must be sent to send an email, and they must be sent in the correct sequence. As a consequence of this, executing multiple sendmail tasks in parallell (i.e. with asyncio.gather) is not any more efficient than executing in sequence, as the client must wait until one mail is sent before beginning the next.

If you have a lot of emails to send, consider creating multiple connections (SMTP instances) and splitting the work between them.

Roadmap

aiosmtplib is now feature complete, however test coverage and documentation need a lot of work. Feature requests and bug reports are welcome via Github issues.