Duva for Python

The official Duva client library for Python. Duva is a transactional email API hosted in Canada.

pip install duva-mail
# or: uv add duva-mail

Requires Python 3.10 or later. Fully typed (py.typed); both a synchronous and an asynchronous client are provided.

Sending a message

from duva import Duva

duva = Duva(api_key="dv_...", domain="example.com")  # or DUVA_API_KEY / DUVA_DOMAIN

message = duva.messages.send(
    from_="Example <notifications@example.com>",
    to=["client@example.org"],
    subject="Your order",
    text="Thank you for your order.",
)
print(message.id, message.status)  # "queued": always asynchronous

The same call, asynchronously:

from duva import AsyncDuva

async with AsyncDuva(api_key="dv_...", domain="example.com") as duva:
    message = await duva.messages.send(
        from_="Example <notifications@example.com>",
        to=["client@example.org"],
        subject="Your order",
        text="Thank you for your order.",
    )

To, Cc and Bcc

to, cc and bcc take addresses or Name <address>. Every copy shows all the to and all the cc; a bcc address appears only on its own copy. The three lists together count against your plan's recipient maximum.

duva.messages.send(
    from_="Example <notifications@example.com>",
    to=["Jean Tremblay <jean@example.org>"],
    cc=["accounting@example.org"],
    bcc=["archive@example.com"],
    subject="Your order",
    text="Thank you for your order.",
)

Reading events and pagination

for event in duva.events.list_all(type="bounced"):
    print(event.type, event.detail.get("recipient"))

events.list() and suppressions.list() return one page (.data, .next_cursor); events.list_all() and suppressions.list_all() are generators that follow next_cursor for you, optionally bounded with max_items=. AsyncDuva's equivalents (list_all) are async generators (async for).

Verifying a webhook

from duva import WebhookSignatureError, construct_event

try:
    event = construct_event(secret, request.headers, raw_body)
    print(event.type, event.data.get("message_id"))
except WebhookSignatureError:
    # respond 400
    ...

raw_body must be the exact bytes Duva sent (your framework's raw-body option, not a re-serialized parsed body): re-encoding it changes the bytes and invalidates the signature. Rotating your webhook secret? Pass a list — construct_event([old_secret, new_secret], ...) — while both are active.

Errors

Every error Duva answers with is a DuvaError subclass; rely on .code (the contract), never on the exception message (its wording can change):

from duva import NotFoundError, QuotaExceededError, ValidationError

try:
    duva.messages.send(...)
except ValidationError as error:
    print(error.fields)  # [{"field": "to[0]", "message": "..."}]
except QuotaExceededError as error:
    print(f"retry in {error.retry_after}s")
except NotFoundError:
    ...  # the API key, domain or resource could not be found

Network failures and timeouts raise DuvaConnectionError / DuvaTimeoutError instead (no HTTP response was ever received). Reads and messages.send (idempotency-key protected) are retried automatically on a transient failure; suppressions.add/remove and webhooks.create/delete are not, because the outcome of a timed-out first attempt is unknown. A 429 quota_exceeded is never retried automatically (its retry_after can be hours); a 429 rate_limited is, as long as the wait fits within max_retry_wait_seconds (30s by default).

Attachments

from duva import Attachment

attachment = Attachment.from_file("./invoice.pdf")
duva.messages.send(..., attachments=[attachment])

Attachment.from_bytes(filename, content, content_type=None, content_id=None) works from data already in memory; content_id turns the attachment into an inline image the HTML references with cid:.

Configuration

Full reference

The complete API surface and the OpenAPI specification this library is generated from: https://duva.ca/en/docs and https://duva.ca/openapi.json.

Development

uv sync --extra dev
uv run --extra dev python scripts/generate.py --local  # regenerate _generated/models.py from a local ../duva checkout
uv run mypy
uv run pytest                                           # unit tests
uv run --extra dev python scripts/fetch_conformance.py && uv run pytest tests/conformance
uv build

This library's request/response models are generated from Duva's OpenAPI specification (src/duva/_generated/, never edited by hand); the client itself (retries, pagination, errors, webhooks) is hand-written and checked against the shared fixtures published in duva-mail/duva-conformance.

License

MIT, see LICENSE.