diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches
index 958182f6aa1f104a22659df31ac3a97ed8bf15cd..302d148c2e18f0e0fe565bc9c9c1a2f4b232d346 100644
--- a/Documentation/SubmittingPatches
+++ b/Documentation/SubmittingPatches
@@ -209,6 +209,19 @@ Exception:  If your mailer is mangling patches then someone may ask
 you to re-send them using MIME.
 
 
+WARNING: Some mailers like Mozilla send your messages with
+---- message header ----
+Content-Type: text/plain; charset=us-ascii; format=flowed
+---- message header ----
+The problem is that "format=flowed" makes some of the mailers
+on receiving side to replace TABs with spaces and do similar
+changes. Thus the patches from you can look corrupted.
+
+To fix this just make your mozilla defaults/pref/mailnews.js file to look like:
+pref("mailnews.send_plaintext_flowed", false); // RFC 2646=======
+pref("mailnews.display.disable_format_flowed_support", true);
+
+
 
 7) E-mail size.