force formatter in MailHandler

src/Options/MailLoggerHandlerOption.php

@@ -18,6 +18,7 @@ declare(strict_types=1);
 namespace D3\LoggerFactory\Options;
 
 use Monolog\Formatter\HtmlFormatter;
+use Monolog\Formatter\LineFormatter;
 use Monolog\Handler\NativeMailerHandler;
 use Monolog\Logger;
 
@@ -39,6 +40,10 @@ class MailLoggerHandlerOption extends AbstractHandlerOption implements HandlerOp
                 ->setContentType('text/html')
                 ->setEncoding('iso-8859-1')
                 ->setFormatter(new HtmlFormatter());
+        } else {
+            $this->handler->setFormatter(
+                new LineFormatter()
+            );
         }
     }
-}
+}