
In the world of object-oriented programming, the quality of the developer experience with SDKs depends on the freedom users have to customize and extend the existing features to suit their needs. The more space for creativity they have, the better.

So, to provide a unique experience sending emails, managing domains and API keys using the JVM (Java Virtual Machine), we developed a Java SDK to expand the capabilities and features of Resend.

## Getting started

To install the Resend Java SDK, add the following dependency to your project:

*Gradle:*

```bash
implementation 'com.resend:resend-java:2.0.0'
```

*Maven:*

```xml
<dependency>
    <groupId>com.resend</groupId>
    <artifactId>resend-java</artifactId>
    <version>2.0.0</version>
</dependency>
```

</CodeGroup>

Construct your email and easily send it by using our client;

```java
package com.resend;

import com.resend.*;

public class Main {
    public static void main(String[] args) {
        String apiKey = "re_123456789";

        Resend client = new Resend(apiKey);

        SendEmailRequest sendEmailRequest = SendEmailRequest.builder()
            .from("Acme <onboarding@resend.dev>")
            .to("delivered@resend.dev")
            .subject("Hello World")
            .html("<strong>It works!</strong>")
            .build();

        SendEmailResponse data = client.emails().send(sendEmailRequest);

        System.out.println(data.getId());
    }
}
```

You can also create new Domains with the Java SDK.

```java
package com.resend;

import com.resend.*;

public class Main {
    public static void main(String[] args) {
        String apiKey = "re_123456789";

        Resend client = new Resend(apiKey);

        CreateDomainRequest params = CreateDomainRequest
                .builder()
                .name("example.com").build();

        CreateDomainResponse domain = client.domains().create(params);
        System.out.println(domain.getId());
    }
}
```

To learn more, take a look in the [documentation](https://resend.com/docs/send-with-java) and try the [full example](https://github.com/resendlabs/resend-java-example).

If you would like to contribute to the Java SDK, check out the [Github repository](https://github.com/resendlabs/resend-java) .

## Next steps

In the future, we aim to expand our capabilities by incorporating additional JVM languages like Kotlin and creating a reactive version of the library to handle Mono and Flux data types.

Now you can send emails using the official Resend SDK for Java apps.

Announcing the Java SDK


Friction is the kind of thing we're constantly exploring how to remove.

We want to make sure that you have all the information you need, and that you can find things quickly. With that in mind, we've decided to bring all of our [API Reference](https://resend.com/docs/api-reference/introduction) documentation into the app.

For example, when you navigate to [Domains](https://resend.com/domains), you can see all of the available methods related to domains right there without having to open a new tab.

<video
  src="/static/posts/in-app-docs.mp4"
  controls
  className="mx-auto mb-4 rounded-lg"
/>

The same goes for other resources like [Emails](https://resend.com/emails) and [API Keys](https://resend.com/api-keys).

We hope this makes your life easier and that you can find what you need faster.

<div class="changelog">

## Other improvements and fixes

**SMTP**

- Fix send attachments

**API**

- Fix `subject` validation
- Fix email address type validation
- Fix email address with colon
- Fix attachment as `base64`
- Fix Chinese characters validation
- Fix ASCII email address
- Validate `tags`

</div>


Easily access all API methods from within the Resend dashboard.

In-App Docs


One of the requirements for you to start sending emails using Resend is to create an API key. This token is used to authenticate your requests, and it's essential to keep it safe.

To give you more control and visibility, we've added a dedicated page for each API key.

## Seeing all API keys

Now you can see the **last time you used** an API key.

By having different color indicators, you can quickly scan and detect which API keys are being used and which ones are not.

![API Keys - Table View](/static/posts/api-key-insights-1.jpg)

## Interacting with an inactive API key

In the event that an API key **hasn't been used in the last 30 days**, we now advise users to consider deleting them to keep their accounts secure.

![API Key - Active View](/static/posts/api-key-insights-2.jpg)

## Viewing an active API key

When visualizing an active API key, you can see the **total number of requests** made and go to a separate Logs page to view them.

![API Key - Active View](/static/posts/api-key-insights-3.jpg)

To see this in practice, go to your [API Keys page](https://resend.com/api-keys) and check it out.


Have more control and visibility over your API usage.

API Key Insights

Send and monitor emails from Supabase Auth using a custom SMTP server.

Supabase Integration

Start integrating with third-party services and sending emails via SMTP.

SMTP Service


Every email that is triggered through Resend generates a series of other events.

These events describe if an email was delivered or not, if it was opened by a user, or if any of the links were clicks. It also informs if the email bounced or if the recipient marked the email as spam.

Now we're surfacing that information in a timeline view so you can see the events of every email that you send.

![Email Events Timeline](/static/posts/email-events-timeline-1.jpg)

As you hover over each event, you can see more details about it.

![Email Events Timeline - Bounced](/static/posts/email-events-timeline-2.jpg)

In the example above, you can see that the email bounced in a transient way, not a permanent way. This means that the email was rejected by the recipient's mail server, but it could be delivered in the future.

This functionality was designed to give you more visibiilty and help you understand in a chronological way what happened to each email that you send.

If you want to see it all in action, check the [Emails](https://resend.com/emails) page.


See the status of every email that you send.

Email Events Timeline


Email headers are typically hidden from the end user but are crucial for deliverability. They include information about the sender, receiver, timestamp, and more.

Resend already includes all the necessary headers for you, but now you can also add your own custom headers.

Here's how you can add custom headers to your emails using the Node.js SDK:

```ts
resend.emails.send({
  from: 'Acme <onboarding@resend.dev>',
  to: ['delivered@resend.dev'],
  subject: 'hello world',
  text: 'it works!',
  headers: {
    'X-Entity-Ref-ID': '123456789',
  },
});
```

This is a fairly advanced feature, but it can be useful for a few things:

- Prevent threading on Gmail with the **`X-Entity-Ref-ID`** header ([Example](https://github.com/resendlabs/resend-examples/tree/main/with-prevent-thread-on-gmail))
- Include a shortcut for users to unsubscribe with the **`List-Unsubscribe`** header ([Example](https://github.com/resendlabs/resend-examples/tree/main/with-unsubscribe-url-header))

If you want to learn more about how to use headers, check the [API documentation](https://resend.com/docs/api-reference/emails/send-email).


Customize how emails are sent with your own headers.

Custom Email Headers


Understanding your emails is a key part of being a good sender. With that in mind, we've improved the [Overview](https://resend.com/overview) graph to help you do just that.

![Overview - Total Emails Sent](/static/posts/improved-overview-metrics-1.jpg)

All of your statistics are aggregated in one place so you can have a high-level view of your email events such as:

- **Delivered**: Emails that were successfully delivered.
- **Opened**: Emails that were opened by the recipient.
- **Clicked**: Emails that were had a link clicked by the recipient.
- **Bounced**: Emails that were rejected by the recipient’s mail server.
- **Complained**: Emails that were delivered but marked as spam by the recipient.

The goal is for you to send better emails with lessons learned from the Resend console.

## New Domains View

On the same page, you can see a breakdown of all the domains you've sent emails from.

![Overview - Breakdown by Domain](/static/posts/improved-overview-metrics-2.jpg)

This is designed for multi-tenant senders who have multiple domains to send emails from the same account, and need to monitor the performance of each domain.

If you want to see it all in action, check the [Overview](https://resend.com/overview) page.


See all of your email statistics in a more granular way.

Improved Overview Metrics


## Why Now?

Over the past few months, we've experienced exciting growth. More than 5,000 senders have joined Resend to deliver their critical transactional emails. This growth has moved us toward specific investments in how we handle load on our API.

To that end, we’re announcing API rate limits.

Every customer will have a rate limit of 10 requests per second by default, which should be sufficient for most use cases. As needed, customers can [request additional rate limit](/contact).

## Transparency

We want to give you the proper tools to work well with this new rate limit, so we’ve added new headers in the API response to show the current usage.

These headers were built in conformance with the [IETF standard](https://datatracker.ietf.org/doc/html/draft-ietf-httpapi-ratelimit-headers) to facilitate adoption:

- **ratelimit-limit**: Maximum number of requests allowed within a window
- **ratelimit-remaining**: How many requests you have left within the current window.
- **ratelimit-reset**: How many seconds until the limits are reset.
- **retry-after**: How many seconds you should wait before making a follow-up request.

If you exceed your rate limit for that window, you’ll receive a **429** response error code.

To prevent this, we recommend reducing the rate at which you request the API. This can be done by introducing a queue mechanism or reducing the number of concurrent requests per second.

If you want to learn more about how rate limits work, check the [API documentation](https://resend.com/docs/api-reference/introduction#rate-limit).


New headers to help you control your API requests.

API Rate Limit


Python's ecosystem is one of the most extensive and vibrant in the programming world. From web development to machine learning and scientific computing.

With Resend's Python SDK, you can now make email sending an easy step in your workflow no matter what type of work you're doing.

## Getting started

```python
pip install resend
```

After installing the Python SDK with `pip`, you'll be able to send your first email in just a few simple steps.

```python
import resend

resend.api_key = os.environ["RESEND_API_KEY"]

email = resend.Emails.send({
    "from": "me@example.com",
    "to": ["user@gmail.com"],
    "subject": "Hello from Python",
    "html": "<strong>Python <3</strong>"
})

print(email)
```

You can also create new API Keys and Domains with the Python SDK.

```python
import resend

resend.api_key = os.environ["RESEND_API_KEY"]

api_key = resend.ApiKeys.create({ "name": "prod" })
print(api_key)

domain = resend.Domains.create({ "name": "domain.io" })
print(domain)
```

If you would like to learn more, check out the [documentation](https://resend.com/docs/send-with-python).

You can also find the examples on [GitHub](https://github.com/resendlabs/resend-python/tree/main/examples).

## Next steps

We'll be releasing new guides soon on integrating our Python SDK with the most popular Python web frameworks like Django and Flask. These guides will show you step-by-step how to seamlessly send emails from your web applications.


Integrate email into your Python apps using the new Resend SDK.

Announcing the Python SDK


During development, it's common to test different scenarios by sending test emails.

Instead of using your personal email account or setting up a fake SMTP server, you can leverage the following email addresses to simulate each event type.

This gives you full use of Resend's Dashboard, Webhooks, and API - without affecting your domain reputation.

## Test delivered emails

To test that your emails are being successfully delivered, you can send an email to:

```
delivered@resend.dev
```

## Test bounced emails

To test that the recipient's email provider rejected your email, you can send an email to:

```
bounced@resend.dev
```

This will generate a SMTP 550 5.1.1 ("Unknown User") response code.

## Test "Marked as Spam" emails

To test that your emails are received but marked as spam, you can send an email to:

```
complained@resend.dev
```


Simulate different events by sending test emails.

Sending test emails


You can now create API keys with limited access to your account.

This is useful if you want to give a third-party access to your account, but don't want to give them full access.

## Types of API keys

There are 2 different permissions of API keys:

- **Full access:** allows the API key to create, delete, get, and update any resource.
- **Sending access:** allows the API key to only send emails.

With API key permissions, Resend users can give each API key different permissions, which can limit the damage that may be done both accidentally or maliciously.

## Creating an API key

1. Navigate to **API Keys** on the sidebar.
2. Click **Create API Key**.
3. Give your API key a name.
4. Select **Full access** or **Sending access** as the permission.
5. If you select **Sending access**, you can choose the specific domain you want restrict access.

![Adding an API key](/static/posts/new-api-key-permissions-1.jpg)

After an API key is created, you can view the API key and its permissions.

![Listing API keys](/static/posts/new-api-key-permissions-2.jpg)

## Using the API

Alternatively, you can use the API to programmatically manage API keys.

Here's how to create API keys using Node.js:

```ts
import { Resend } from 'resend';

const resend = new Resend('re_123456789');

resend.apiKeys.create({
  name: 'Production',
  permission: 'full_access',
});
```

Check the documentation to learn how to [create](https://resend.com/docs/api-reference/api-keys/create-api-key), [list](https://resend.com/docs/api-reference/api-keys/list-api-keys), and [delete API keys](https://resend.com/docs/api-reference/api-keys/delete-api-key) using the API.


Easily secure your account access with different permissions.

New API Key Permissions


Providing the best developer experience is one of our main focuses at Resend. We believe the best way to integrate with Resend is using one of our many SDK's to interact with the REST API. Today, we are thrilled to announce the launch of our PHP SDK.

## The story

It all started with a simple question: _“How can I send emails when I’m using PHP?”_. Resend already has a very simple API endpoint to send emails, so why not using that?

I thought creating a wrapper would allow me to use it for my other PHP apps and now we're sharing this package with everyone interested in integrating Resend with PHP.

## Working with PHP

First, install the client via Composer:

```bash
composer require resend/resend-php
```

Then, interact with Resend's API:

```php
$resend = Resend::client('re_123456789');

try {
    $result = $resend->sendEmail([
        'from' => 'noreply@example.com',
        'to' => 'user@gmail.com',
        'subject' => 'hello world',
        'text' => 'it works!',
        'html' => '<strong>it works!</strong>',
    ]);
} catch (\Exception $e) {
    exit('Error: ' . $e->getMessage());
}

echo $result->toArray();
```

If you would like to learn more about the PHP SDK, check out the [documentation](https://resend.com/docs/send-with-php).

You can also find the source code on [GitHub](https://github.com/resendlabs/resend-php).

## Future plans

While the PHP SDK is ideal for a majority of PHP projects, we would like to take things further by adding support for popular PHP frameworks. In the background we’re working away at building Resend for Laravel, designed on top of the new PHP SDK to easily integrate with your application.

Here's the work-in-progress repository for Laravel, in case you're curious: [https://github.com/resendlabs/resend-laravel](https://github.com/resendlabs/resend-laravel)


Now you can send emails using the official Resend SDK for PHP apps.

Changelog