Compose, deliver and test your emails easily in Elixir.
We have applied the lessons learned from projects like Plug, Ecto and Phoenix in designing clean and composable APIs, with clear separation of concerns between modules. Swoosh comes with 12 adapters, including SendGrid, Mandrill, Mailgun, Postmark and SMTP. See the full list of adapters below.
The complete documentation for Swoosh is available online at HexDocs.
Elixir 1.10+ and Erlang OTP 22+
# In your config/config.exs file
config :sample, Sample.Mailer,
adapter: Swoosh.Adapters.Sendgrid,
api_key: "SG.x.x"
# In your application code
defmodule Sample.Mailer do
use Swoosh.Mailer, otp_app: :sample
end
defmodule Sample.UserEmail do
import Swoosh.Email
def welcome(user) do
new()
|> to({user.name, user.email})
|> from({"Dr B Banner", "[email protected]"})
|> subject("Hello, Avengers!")
|> html_body("<h1>Hello #{user.name}</h1>")
|> text_body("Hello #{user.name}\n")
end
end
# In an IEx session
email = Sample.UserEmail.welcome(%{name: "Tony Stark", email: "[email protected]"})
Sample.Mailer.deliver(email)
# Or in a Phoenix controller
defmodule Sample.UserController do
use Phoenix.Controller
alias Sample.UserEmail
alias Sample.Mailer
def create(conn, params) do
user = create_user!(params)
UserEmail.welcome(user) |> Mailer.deliver()
end
end
See Swoosh.Mailer
for more
configuration options.
-
Add swoosh to your list of dependencies in
mix.exs
:def deps do [{:swoosh, "~> 1.6"}] end
-
(Optional-ish) Most adapters (non SMTP ones) use
Swoosh.ApiClient
to talk to the service provider. Swoosh comes withSwoosh.ApiClient.Hackney
configured by default. If you want to use it, you just need to includeHackney
as a dependency of your app.Swoosh also accepts
Finch
out-of-the-box. SeeSwoosh.ApiClient.Finch
for details.If you need to integrate with another HTTP client, it's easy to define a new API client. Follow the
Swoosh.ApiClient
behaviour and configure Swoosh to use it:config :swoosh, :api_client, MyApp.ApiClient
But if you don't need
Swoosh.ApiClient
, you can disable it by setting the value tofalse
:config :swoosh, :api_client, false
This is the case when you are using
Swoosh.Adapters.Local
,Swoosh.Adapters.Test
and adapters that are SMTP based, that don't require an API client. -
(Optional) If you are using
Swoosh.Adapters.SMTP
,Swoosh.Adapters.Sendmail
orSwoosh.Adapters.AmazonSES
, you also need to addgen_smtp
to your dependencies:def deps do [ {:swoosh, "~> 1.6"}, {:gen_smtp, "~> 1.0"} ] end
Swoosh supports the most popular transactional email providers out of the box and also has a SMTP adapter. Below is the list of the adapters currently included:
Provider | Swoosh adapter |
---|---|
SMTP | Swoosh.Adapters.SMTP |
SendGrid | Swoosh.Adapters.Sendgrid |
Sendinblue | Swoosh.Adapters.Sendinblue |
Sendmail | Swoosh.Adapters.Sendmail |
Mandrill | Swoosh.Adapters.Mandrill |
Mailgun | Swoosh.Adapters.Mailgun |
Mailjet | Swoosh.Adapters.Mailjet |
Postmark | Swoosh.Adapters.Postmark |
SparkPost | Swoosh.Adapters.SparkPost |
Amazon SES | Swoosh.Adapters.AmazonSES |
Dyn | Swoosh.Adapters.Dyn |
SocketLabs | Swoosh.Adapters.SocketLabs |
Gmail | Swoosh.Adapters.Gmail |
MailPace | Swoosh.Adapters.MailPace |
Configure which adapter you want to use by updating your config/config.exs
file:
config :sample, Sample.Mailer,
adapter: Swoosh.Adapters.SMTP
# adapter config (api keys, etc.)
Check the documentation of the adapter you want to use for more specific configurations and instructions.
Adding new adapters is super easy and we are definitely looking for contributions on that front. Get in touch if you want to help!
The Recipient Protocol enables you to easily make your structs compatible with Swoosh functions.
defmodule MyUser do
@derive {Swoosh.Email.Recipient, name: :name, address: :email}
defstruct [:name, :email, :other_props]
end
Now you can directly pass %MyUser{}
to from
, to
, cc
, bcc
, etc.
See Swoosh.Email.Recipient
for more details.
Swoosh does not make any special arrangements for sending emails in a non-blocking manner. Opposite to some stacks, sending emails, talking to third party apps, etc in Elixir do not block or interfere with other requests, so you should resort to async emails only when necessary.
One simple way to deliver emails asynchronously is by leveraging Elixir's
standard library. First add a Task supervisor to your application root,
usually at lib/my_app/application.ex
:
def start(_, _) do
children = [
...,
# Before the endpoint
{Task.Supervisor, name: MyApp.AsyncEmailSupervisor},
MyApp.Endpoint
]
Supervisor.start_link(children, strategy: :one_for_one)
end
Now, whenever you want to send an email:
Task.Supervisor.start_child(MyApp.AsyncEmailSupervisor, fn ->
%{name: "Tony Stark", email: "[email protected]"}
|> Sample.UserEmail.welcome()
|> Sample.Mailer.deliver()
end)
Please take a look at the official docs for Task and Task.Supervisor for further options.
One of the downsides of sending email asynchronously is that failures won't be reported to the user, who won't have an opportunity to try again immediately, and tasks by default do not retry on errors. Therefore, if the email must be delivered asynchronously, a safer solution would be to use a queue or job system. Elixir's ecosystem has many job queue libraries.
- Oban is the current community favourite. It uses PostgreSQL for storage and coordination.
- Exq uses Redis and is compatible with Resque / Sidekiq.
If you are looking to use Swoosh in your Phoenix project, make sure to check out the phoenix_swoosh project. It contains a set of functions that make it easy to render the text and HTML bodies using Phoenix views, templates and layouts.
Taking the example from above the "Getting Started" section, your code would look something like this:
web/templates/layout/email.html.eex
<html>
<head>
<title><%= @email.subject %></title>
</head>
<body>
<%= @inner_content %>
</body>
</html>
web/templates/email/welcome.html.eex
<div>
<h1>Welcome to Sample, <%= @username %>!</h1>
</div>
web/emails/user_email.ex
defmodule Sample.UserEmail do
use Phoenix.Swoosh, view: Sample.EmailView, layout: {Sample.LayoutView, :email}
def welcome(user) do
new()
|> to({user.name, user.email})
|> from({"Dr B Banner", "[email protected]"})
|> subject("Hello, Avengers!")
|> render_body("welcome.html", %{username: user.username})
end
end
Feels familiar doesn't it? Head to the phoenix_swoosh repo for more details.
You can attach files to your email using the Swoosh.Email.attachment/2
function. Just give the path of your file as an argument and we will do the
rest. It also works with a %Plug.Upload{}
struct, or a %Swoosh.Attachment{}
struct, which can be constructed using Swoosh.Attachment.new
detailed here in
the docs.
All built-in adapters have support for attachments.
new()
|> to("[email protected]")
|> from({"Jarvis", "[email protected]"})
|> subject("Invoice May")
|> text_body("Here is the invoice for your superhero services in May.")
|> attachment("/Users/jarvis/invoice-peter-may.pdf")
In your config/test.exs
file set your mailer's adapter to
Swoosh.Adapters.Test
so that you can use the assertions provided by Swoosh in
Swoosh.TestAssertions
module.
defmodule Sample.UserTest do
use ExUnit.Case, async: true
import Swoosh.TestAssertions
test "send email on user signup" do
# Assuming `create_user` creates a new user then sends out a `Sample.UserEmail.welcome` email
user = create_user(%{username: "ironman", email: "[email protected]"})
assert_email_sent Sample.UserEmail.welcome(user)
end
end
Swoosh ships with a Plug that allows you to preview the emails in the local (in-memory) mailbox. It's particularly convenient in development when you want to check what your email will look like while testing the various flows of your application.
For email to reach this mailbox you will need to set your Mailer
adapter to
Swoosh.Adapters.Local
:
# in config/dev.exs
config :sample, MyApp.Mailer,
adapter: Swoosh.Adapters.Local
In your Phoenix project you can forward
directly to the plug
without spinning up a separate webserver, like this:
# in web/router.ex
if Mix.env == :dev do
scope "/dev" do
pipe_through [:browser]
forward "/mailbox", Plug.Swoosh.MailboxPreview
end
end
You can also start a new server if your application does not depends on Phoenix:
# in config/dev.exs
# to run the preview server alongside your app
# which may not have a web interface already
config :swoosh, serve_mailbox: true
# in config/dev.exs
# to change the preview server port (4000 by default)
config :swoosh, serve_mailbox: true, preview_port: 4001
When using serve_mailbox: true
make sure to have plug_cowboy
as a
dependency of your app.
{:plug_cowboy, ">= 1.0.0"}
And finally you can also use the following Mix task to start the mailbox preview server independently:
$ mix swoosh.mailbox.server
Note: the mailbox preview won't display emails
being sent from outside its own node. So if you are testing using an IEx
session,
it's recommended to boot the application in the same session.
iex -S mix phx.server
or iex -S mix swoosh.mailbox.server
will do the trick.
If you are curious, this is how it the mailbox preview looks like:
The preview is also available as a JSON endpoint.
$ curl http://localhost:4000/dev/mailbox/json
Swoosh starts a memory storage process for local adapter by default. Normally it does no harm being left around in production. However, if it is causing problems, or you don't like having it around, it can be disabled like so:
# config/prod.exs
config :swoosh, local: false
The following events are emitted:
[:swoosh, :deliver, :start]
: occurs whenMailer.deliver/2
begins.[:swoosh, :deliver, :stop]
: occurs whenMailer.deliver/2
completes.[:swoosh, :deliver, :exception]
: occurs whenMailer.deliver/2
throws an exception.[:swoosh, :deliver_many, :start]
: occurs whenMailer.deliver_many/2
begins.[:swoosh, :deliver_many, :stop]
: occurs whenMailer.deliver_many/2
completes.[:swoosh, :deliver_many, :exception]
: occurs whenMailer.deliver_many/2
throws an exception.
View example in docs
Documentation is written into the library, you will find it in the source code,
accessible from iex
and of course, it all gets published to
HexDocs.
We are grateful for any contributions. Before you submit an issue or a pull request, remember to:
- Look at our Contributing guidelines
- Not use the issue tracker for help or support requests (try StackOverflow, IRC or Slack instead)
- Do a quick search in the issue tracker to make sure the issues hasn't been reported yet.
- Look and follow the Code of Conduct. Be nice and have fun!
Clone the repo and fetch its dependencies:
$ git clone https://github.com/swoosh/swoosh.git
$ cd swoosh
$ mix deps.get
$ mix test
$ MIX_ENV=docs mix docs
See LICENSE