Ignored Resend rate limiting, Laravel failover configuration doesn't work

[MrMarci666]

Intro

Hello there,

We experienced many issues with this package, because it is simply ignoring the rate limitation of Resend.

By default, Resend has a rate limit of 2 requests per second for API calls. 1 This rate limit is designed to manage the load on their API and ensure fair usage across all customers.

However, Resend understands that some users may need higher rate limits for their specific use cases. If you find that the default rate limit is not sufficient for your needs, you have the option to request an increase. To request a rate limit increase, you should contact Resend support. Here's what you need to know:

The default rate limit can be increased for trusted senders upon request. 2. If you have specific requirements that exceed the default limit, you should reach out to Resend support to discuss your needs. 3. You can contact Resend support through their website at https://resend.com/contact to request a rate increase. It's worth noting that Resend provides response headers that help you monitor your current rate limit usage. These headers include:

• 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 These headers can help you manage your API requests and avoid hitting the rate limit.

If you do exceed the rate limit, you'll receive a 429 response error code. To prevent this, Resend recommends implementing strategies such as introducing a queue mechanism or reducing the number of concurrent requests per second. Remember, while requesting a rate limit increase is possible, it's also important to optimize your API usage to work efficiently within the provided limits when possible.

We are using a "Failover" configuration in Laravel 11.

'failover' => [
  'transport' => 'failover',
  'mailers' => [
    'resend',
    'smtp',
    'log',
  ],
],

Expected behaviour

I expect when I want to send out E-Mails using Resend mail driver in Laravel, it should work. If Resend has a built-in 2 requests per second rate limit, and also rate limit information response headers, the package should be prepared to read and use this information, and send out the mails via Resend correctly.

Also, if the requests fails, Laravel should use the next E-Mail sending method configured in the failover configuration. I am not sure that this is a Laravel issue or a Resend package issue, but it doesn't work right now, if the response is 429 from Resend, Laravel won't try to send out with the next configured E-Mail sender.

Issue description, screenshots

So we just released a webshop with around 15.000 users and wanted to send them a Password Change E-Mail. However, this resulted with a disaster that the Resend API responded with 429 in many cases, and Laravel didn't try to send it out with the failover SMTP server, it just threw an error... 👎