I just upgraded to Laravel 5.7 and now I am using the built in Email Verification. However there is 2 things I have not been able to figure out and the primary issue is how
Building slightly on the answer by Andrew Earls, you can also publish all the markdown mail components used by the application with this command:
php artisan vendor:publish --tag=laravel-mail
Once that's done you'll have a series of html and markdown files to modify in resources/views/vendor/mail. This will allow you to modify the overall email layout and also 'theme' the CSS. I'd highly recommend having a good read of the Mail docs - Customizing The Components.
As a general email theming quick-start (Laravel 5.7), you can:
php artisan vendor:publish --tag=laravel-mail .resources/views/vendor/mail/html/themes/default.css to your own file. e.g resources/views/vendor/mail/html/themes/wayne.cssconfig/mail.php and where you see 'theme' => 'default' change it to 'theme' => 'wayne'wayne.css to restyle your emails.Hope that helps someone.