Upgrade to Laravel 9

app/CustomMailDriver/Mime/Encoder/RawContentEncoder.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\CustomMailDriver\Mime\Encoder;
+
+use Symfony\Component\Mime\Encoder\ContentEncoderInterface;
+
+final class RawContentEncoder implements ContentEncoderInterface
+{
+    public function encodeByteStream($stream, int $maxLineLength = 0): iterable
+    {
+        while (!feof($stream)) {
+            yield fread($stream, 8192);
+        }
+    }
+
+    public function getName(): string
+    {
+        return 'raw';
+    }
+
+    public function encodeString(string $string, ?string $charset = 'utf-8', int $firstLineOffset = 0, int $maxLineLength = 0): string
+    {
+        return $string;
+    }
+}