CakePHP 3.x - Email to log instead of sending during debug - email

Question

I would like to switch my application to a configuration where email isn't actually send, but instead saved to a log file.
This way I can test my application normally without being afraid of accidentally emailing to hundreds of users and without spamming myself.
I figured something with EmailTransports could be a solution. For instance, when using the DebugTransport the emails aren't send at all, the mail content is instead only returned by the ->send() function.
The downside of this transport is than I have to modify controller code in order to display the content, which I would like to avoid.
So is there a configuration such that email is stored to files instead of being sent, e.g.:
[root]
logs/
emails/
2019-10-01_15:32_email#example.com.txt
2019-10-01_16:54_another_recipient#example.com.txt
...

Answer 1

There is no such built-in configuration, no, but you can easily create your own custom transport that logs emails to files instead of sending them.
Here's a very basic example transport that extends the debug transport, and writes the data to a custom logging scope:
namespace App\Mailer\Transport;
use Cake\Log\LogTrait;
use Cake\Mailer\Email;
use Cake\Mailer\Transport\DebugTransport;
use Psr\Log\LogLevel;
class TestTransport extends DebugTransport
{
use LogTrait;
public function send(Email $email)
{
$data = parent::send($email);
$this->log(json_encode($data), LogLevel::DEBUG, ['scope' => ['emails']]);
return $data;
}
}
See also
Cookbook > Email > Using Transports > Creating Custom Transports