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

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

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.

For debugging only!
If you don't expect more then 5 emails and don't have the option to change mailtrap, try:

foreach ($emails as $email) {    ...    Mail::send(... $email);                                                                          if(env('MAIL_HOST', false) == 'smtp.mailtrap.io'){        sleep(1); //use usleep(500000) for half a second or less    }}

Using sleep() is a really bad practice. In theory this code should only execute in test environment or in debug mode.