Right. Now assuming your the same guy I was helping earlier in IRC. I got the same error as you and I fixed it.

Here are the steps I took: (Step 4 is the most important).

1) Install Lumen:
lumen new service

2) Include the Mail libs:
composer require illuminate\mail

3) add test mail call to the provided '/' route in route.php
Mail::raw('Raw string email', function($msg) { $msg->to(['x@x.com']); $msg->from(['x@x.com']); });

4) uncomment lines in bootstrap/app.php
line 81 and line 22 need to be uncommented.
$app->register('App\Providers\AppServiceProvider'); to access the Mail ServiceProvider.
$app->withFacades(); to access the Mail facade.

5) profit.

This should work now, provided the correct settings are provided for the email provider (username, port, host etc) No more errors. :)

it is work for me thanks nicekiwi

Where to put the email setting? (username, password, port, etc.) Is it on .env? Assuming i want to use the Mail in my Controller. How can i import or use the Mail Class? Is the code below correct?

use Mail;

nicekiwi said:

2) Include the Mail libs:
composer require illuminate\mail

It should be: composer require illuminate/mail

("/" instead of "").