So I'm using Laravel 5.1 and trying to integrate with Mailgun. Well, that's easy, but now I'm trying to send [custom variables](https://documentation.mailgun.com/user_manual.html#attaching-data-to-messages) from my application along with my emails.

I'm actually switching our application over from Mandrill because of their "new direction" and such. With them, I could supply the variables and tags via the email headers, but with Mailgun, that only works when you send via SMTP. In Laravel, `Mail::send()` uses an API call, so in theory I'd add the metadata there with `"v:my-custom-data" => "{"this_id": 123}"`, but I'd like to avoid altering core classes like that.

I also considered using [Bogardo/Mailgun](https://github.com/Bogardo/Mailgun), but then I'd have to replace all the `Mail::send()`s with `Mailgun::send()`, and then I couldn't send emails locally (environment based email driver), and then the application would be "married" to Mailgun.

Anyone done this before? Please let me know if I'm not clear here.