[7.x] Add Mailgun and Postmark mailer

[mvdnbrk]

No description provided.

[crynobone]

Have a feeling that the documentation is outdated

https://laravel.com/docs/7.x/mail#introduction

[driesvints]

@mvdnbrk can you confirm that the example in the docs isn't working for you?

[crynobone]

@driesvints I'm might be confused when the documentation asking to edit mail.php or services.php.

[driesvints]

@crynobone ah yeah, the docs there are for services.php.