Laravel email with queue 550 error (too many emails per second)

Question

Our emails are failing to send using Laravel with a Redis Queue.

The code that triggers the error is this: ->onQueue('emails')

$job = (new SendNewEmail($sender, $recipients))->onQueue('emails');
$job_result = $this->dispatch($job);

In combination with this in the job:

use InteractsWithQueue;

Our error message is:

Feb 09 17:15:57 laravel: message repeated 7947 times: [ production.ERROR: exception 'Swift_TransportException' with message 'Expected response code 354 but got code "550", with message "550 5.7.0 Requested action not taken: too many emails per second "' in /home/laravel/app/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php:383 Stack trace: #0 /home/laravel/app/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php(281): 

Our error only happens using Sendgrid and not Mailtrap, which spoofs emailing sending. I've talked with Sendgrid and the emails never touched their servers and their service was fully active when my error occurred. So, the error appears to be on my end.

Any thoughts?

Answer 1

I finally figured out how to set up the entire Laravel app to throttle mail based on a config.

In the boot() function of AppServiceProvider,

$throttleRate = config('mail.throttleToMessagesPerMin');
if ($throttleRate) {
    $throttlerPlugin = new \Swift_Plugins_ThrottlerPlugin($throttleRate, \Swift_Plugins_ThrottlerPlugin::MESSAGES_PER_MINUTE);
    Mail::getSwiftMailer()->registerPlugin($throttlerPlugin);
}

In config/mail.php, add this line:

'throttleToMessagesPerMin' => env('MAIL_THROTTLE_TO_MESSAGES_PER_MIN', null), //https://mailtrap.io has a rate limit of 2 emails/sec per inbox, but consider being even more conservative.

In your .env files, add a line like:

MAIL_THROTTLE_TO_MESSAGES_PER_MIN=50

The only problem is that it doesn't seem to affect mail sent via the later() function if QUEUE_DRIVER=sync.

Answer 2

Seems like only Mailtrap sends this error, so either open another account or upgrade to a paid plan.