在Laravel 5.3中添加用于密码重置的Mailgun标记

I'm using Laravel's built in login system (php artisan make:auth) and I linked my Mailgun account for sending reset emails. But how can I define tags?

According to Mailgun's documentation tag needs to be added to function that sends emails.

https://documentation.mailgun.com/user_manual.html#tagging

'o:tag'   => 'Password reset'

Where can I find that function and how to add o:tag into it?

You can do it with headers. I am using Laravel 5.5 with Mailable

public function build()
{
    $emailData = [
        'subject'       => $this->data['subject'],
        'groupName'     => $this->data['groupName'],
        'acceptUrl'     => $this->data['acceptUrl'],
        'declineUrl'    => $this->data['declineUrl'],
        'email'         => $this->data['email'],
    ];

    return $this
        ->subject($this->data['subject'])
        ->markdown('emails.group.invitation')
        ->with($emailData)
        ->withSwiftMessage(function($message) {
            $headers = $message->getHeaders();
            $headers->addTextHeader("X-Mailgun-Variables", '{"type": "group-invitation"}');
            $headers->addTextHeader("X-Mailgun-Tag", "group-invitation");
        });
}