[BUGFIX] Add attached files to the mail queue record

Classes/Service/MailTemplateService.php

@@ -635,11 +635,20 @@ class MailTemplateService {
 	/**
 	 * Add a file resource as attachment
 	 *
-	 * @param FileInterface $file
+	 * @param FileInterface|FileReference $file
 	 * @return MailTemplateService
 	 */
-	public function addFileResourceAttachment(FileInterface $file) {
-		return $this->addAttachment($file->getContents(), $file->getName(), $file->getMimeType());
+	public function addFileResourceAttachment($file) {
+		if ($file instanceof FileReference) {
+			$this->markers[] = $file;
+			$file = $file->getOriginalResource()->getOriginalFile();
+		} elseif ($file instanceof FileInterface) {
+			$fileReference = $this->objectManager->get(FileReference::class);
+			$fileReference->setOriginalResource($file);
+			$this->markers[] = $fileReference;
+		}
+		$this->addAttachment($file->getContents(), $file->getName(), $file->getMimeType());
+		return $this;
 	}
 
 	/**