An adapter that sends email using the MailerSend API.

For reference: MailerSend API docs

This adapter requires an API Client. Swoosh comes with Hackney, Finch and Req out of the box. See the installation section for details.

Example

# config/config.exs
config :sample, Sample.Mailer,
  adapter: Swoosh.Adapters.Mailersend,
  api_key: "your-api-key"

# lib/sample/mailer.ex
defmodule Sample.Mailer do
  use Swoosh.Mailer, otp_app: :sample
end

Using with provider options

import Swoosh.Email

new()
|> from({"T Stark", "tony.stark@example.com"})
|> to({"Steve Rogers", "steve.rogers@example.com"})
|> subject("Hello, Avengers!")
|> html_body("<h1>Hello</h1>")
|> text_body("Hello")
|> put_provider_option(:tags, ["onboarding", "welcome"])
|> put_provider_option(:track_opens, true)
|> put_provider_option(:track_clicks, true)
|> put_provider_option(:metadata, %{"user_id" => "123"})

Using with MailerSend templates

import Swoosh.Email

new()
|> from({"T Stark", "tony.stark@example.com"})
|> to({"Steve Rogers", "steve.rogers@example.com"})
|> put_provider_option(:template_id, "template-123")
|> put_provider_option(:template_variables, %{
  "name" => "Steve",
  "mission" => "Project Insight"
})

Personalization without templates

MailerSend supports {{ variable }} substitution in subject, HTML, and text body fields without requiring a template.

import Swoosh.Email

new()
|> from({"T Stark", "tony.stark@example.com"})
|> to({"Steve Rogers", "steve.rogers@example.com"})
|> subject("Welcome {{ name }}!")
|> html_body("<h1>Hello {{ name }}</h1>")
|> put_provider_option(:personalization, [
  %{"email" => "steve.rogers@example.com", "data" => %{"name" => "Steve"}}
])

Provider Options

• :template_id (string) - MailerSend template ID to use instead of html/text body

• :template_variables (map) - variables for template personalization, applied to all recipients via the personalization array

• :personalization (list of maps) - per-recipient personalization data for non-template emails. Each map must have "email" and "data" keys. Values populate {{ variable }} placeholders in subject, HTML, and text

• :tags (list of strings) - tags to categorize the email (max 5)

• :webhook_id (string) - webhook ID for delivery tracking

• :metadata (map) - custom metadata to attach to the email

• :send_at (integer or DateTime) - unix timestamp or DateTime for scheduled sending

• :track_opens (boolean) - enable open tracking

• :track_clicks (boolean) - enable click tracking

• :track_content (boolean) - enable content tracking

• :in_reply_to (string) - Message-ID of the email being replied to

• :references (list of strings) - list of Message-IDs that the current email is referencing

• :precedence_bulk (boolean) - set precedence bulk header, overrides domain's advanced settings

• :list_unsubscribe (string) - List-Unsubscribe header value per RFC 8058