Mail middleware

[jameslkingsley]

Is there scope to add middleware to the Mail system in Laravel? This would work the same as it does elsewhere in the framework, offering a way to continue or back out of a process.

Reasons why you'd want mail middleware:

• Ensure emails aren't being sent to unsubscribed addresses
• Ensure email addresses are valid
• Ensure business cases are accounted for (eg. do not send after 5pm)

Ideally the middleware would be checked before Laravel starts interacting with the Swift mailer, so that the middleware is being called early enough to be useful still. I say this because the Swift mailer can be a tricky beast to tame especially if you want to validate email addresses before Swift does so itself and throws an exception.

How would it be used?

Fluently:

Mail::to('[email protected]')
    ->through(EnsureEmailAddressIsSubscribed::class)
    ->send(new Mailable);

Config:

// config/mail.php
return [
    'middleware' => [
        \App\Mail\Middleware\EnsureEmailAddressIsValid::class,
        \App\Mail\Middleware\EnsureEmailAddressIsSubscribed::class,
    ],
];

Mailable:

class WelcomeMail extends Mailable
{
    public function middleware()
    {
        return [
            EnsureEmailAddressIsSubscribed::class,
        ];
    }
}

And then the middleware itself would receive the mailable instance, with the ability to see the recipients, view etc.

An alternative change to mail to support this indirectly would be more DI usage throughout the MailManager and Mailer classes, as right now you have to adopt hacky approaches to override them.