diff --git a/Classes/Service/MailTemplateService.php b/Classes/Service/MailTemplateService.php
index 57e1f152903415a8e85db5b056507e70e47d1bf0..9bf4ef2a3454c5e9a6a0f3ab6d0312ae2365524f 100644
--- a/Classes/Service/MailTemplateService.php
+++ b/Classes/Service/MailTemplateService.php
@@ -583,6 +583,8 @@ class MailTemplateService {
 	}
 
 	/**
+	 * IMPORTANT: make sure to set $this->>ignoreMailQueue(TRUE), if you're using this method to add an attachment!
+	 * Otherwise the attachment is ignored when sending the mail via mail queue.
 	 * @param Swift_OutputByteStream $data
 	 * @param string $filename
 	 * @param string $contentType