aiosmtplib
asyncio SMTP client
Decision gist · record as of 2026-08-14
Yes. aiosmtplib is actively maintained, has no dependencies, carries a permissive MIT license, and fills a clear gap for async Python applications that need SMTP. The low install friction and stable production status make it a straightforward choice if you're already using asyncio and need to send email without blocking.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.10 or later.
- Low install friction with no runtime dependencies.
- Active maintenance: last commit 2026-08-06, release 55 days ago.
License · maintenance · safety
MIT (permissive) — MIT license permits commercial and private use with minimal restrictions; you may use, modify, and distribute aiosmtplib freely provided you retain the license notice.
last release 2026-06-20 (55 days) · last repo commit 2026-08-06 · 430 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 19,588,512 downloads/mo, #1,059 on PyPI
Alternatives
Verify before relying
import asyncio
from email.message import EmailMessage
import aiosmtplib
message = EmailMessage()
message["From"] = "root@localhost"
message["To"] = "somebody@example.com"
message["Subject"] = "Hello World!"
message.set_content("Sent via aiosmtplib")
asyncio.run(aiosmtplib.send(message, hostname="127.0.0.1", port=25))- Whether TLS/SSL support is included and how to configure it
- Authentication method support (PLAIN, LOGIN, etc.) and configuration
- Connection pooling or session management capabilities
What it is and what it does
aiosmtplib is a pure-Python SMTP client built for asyncio that lets you send email without blocking your event loop. Unlike the standard library's synchronous smtplib, it integrates directly into async/await code, making it suitable for applications that handle many concurrent operations—web servers, task queues, or any asyncio-based system that needs to send mail.
The package has no runtime dependencies and installs as a single wheel. It wraps the SMTP protocol in async methods, so you construct an EmailMessage using the standard library's email.message module, then pass it to aiosmtplib.send() or manage a connection manually. Requires Python 3.10 or later.
Use it for
- Send transactional emails from a FastAPI or Starlette web application without blocking request handlers
- Batch email delivery in an asyncio task queue or background job system
- Integrate email notifications into an async event-driven architecture
- Concurrent mail operations where multiple messages are sent in parallel within a single event loop
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
aiosmtplib is actively maintained, has no dependencies, carries a permissive MIT license, and fills a clear gap for async Python applications that need SMTP. The low install friction and stable production status make it a straightforward choice if you're already using asyncio and need to send email without blocking.
Install
aiosmtplib on PyPI
Before you install
Low install friction with no runtime dependencies. Active maintenance: last commit 2026-08-06, release 55 days ago. Stable production status since first release in 2016.
Requires Python 3.10 or later.
License in practice
MIT license permits commercial and private use with minimal restrictions; you may use, modify, and distribute aiosmtplib freely provided you retain the license notice.
Quickstart
import asyncio
from email.message import EmailMessage
import aiosmtplib
message = EmailMessage()
message["From"] = "root@localhost"
message["To"] = "somebody@example.com"
message["Subject"] = "Hello World!"
message.set_content("Sent via aiosmtplib")
asyncio.run(aiosmtplib.send(message, hostname="127.0.0.1", port=25))Verify before relying
- Whether TLS/SSL support is included and how to configure it
- Authentication method support (PLAIN, LOGIN, etc.) and configuration
- Connection pooling or session management capabilities
Package facts
| License | MIT permissive |
| Python support | Supports the current Python release >=3.10 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 55 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 19,588,512 / month, #1,059 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableEnvironment :: No Input/Output (Daemon)Framework :: AsyncIOIntended Audience :: DevelopersNatural Language :: EnglishOperating System :: OS IndependentTopic :: CommunicationsTopic :: Communications :: EmailTopic :: Software Development :: LibrariesTopic :: Software Development :: Libraries :: Python ModulesTyping :: Typed |
Evidence: aiosmtplib-5.1.2-py3-none-any.whl
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See also aiosmtpd · yagmail · fastapi-mail · IMAPClient · pyserial-asyncio · aioimaplib · aiopg · aiomysql · apache-airflow-providers-smtp · aiomcache