Lumen 5.6 - Sending mail does show only headers

Hello there, I am sending an email with my lumen 5.6 application to my log. Its configured to my log file for testing purposes. Everything I can see in my log file ist something like headers, subject, from, etc... but not the "content" of the mail. I am using Mailables with "return $this->view(...)".

Can anyone help me?