# Send emails with Sinatra

## Prerequisites

Before you start, you'll need:

- A Resend [API key](/guides/get-started-create-an-api-key)
- A [verified domain](/guides/get-started-add-a-domain)

## Guide

:::::steps
::::step{title="Install"}
Get the Resend Ruby SDK.

:::code-group
```bash RubyGems theme={"theme":{"light":"github-light","dark":"vesper"}}
gem install resend
```

```bash Gemfile theme={"theme":{"light":"github-light","dark":"vesper"}}
gem 'resend'
```
:::
::::

:::step{title="Send email using HTML"}
The easiest way to send an email is by using the `html` parameter.

```rb index.rb theme={"theme":{"light":"github-light","dark":"vesper"}}
require "sinatra"
require "resend"

set :port, 5000
set :bind, "0.0.0.0"

Resend.api_key = ENV["RESEND_API_KEY"]

get "/" do

  content_type :json

  params = {
    from: 'Acme <onboarding@resend.dev>',
    to: ['delivered@resend.dev'],
    subject: 'hello world',
    html: '<strong>it works!</strong>',
  }

  Resend::Emails.send(params).to_hash.to_json
end
```
:::
:::::

## Examples

::::card-grid
:::card{title="Sinatra App" href="https://github.com/resend/resend-examples/tree/main/ruby-resend-examples/sinatra_app" icon="arrow-up-right-from-square"}
Full Sinatra web application
:::

:::card{title="Basic Send" href="https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/basic_send.rb" icon="arrow-up-right-from-square"}
Basic email sending
:::

:::card{title="Attachments" href="https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/with_attachments.rb" icon="arrow-up-right-from-square"}
Send emails with file attachments
:::

:::card{title="Templates" href="https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/with_template.rb" icon="arrow-up-right-from-square"}
Send emails using Resend hosted templates
:::

:::card{title="Scheduling" href="https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/scheduled_send.rb" icon="arrow-up-right-from-square"}
Schedule emails for future delivery
:::

:::card{title="Audiences" href="https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/audiences.rb" icon="arrow-up-right-from-square"}
Manage contacts and audiences
:::

:::card{title="Domains" href="https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/domains.rb" icon="arrow-up-right-from-square"}
Create and manage sending domains
:::

:::card{title="Inbound Webhooks" href="https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/inbound.rb" icon="arrow-up-right-from-square"}
Receive and process inbound emails
:::

:::card{title="Double Opt-in" href="https://github.com/resend/resend-examples/tree/main/ruby-resend-examples/examples/double_optin" icon="arrow-up-right-from-square"}
Double opt-in subscription flow
:::
::::

## Related pages

- [Send emails with Ruby](./get-started-send-with-ruby.md)
- [Send emails with Rails](./get-started-send-with-rails.md)

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