Documentation/email-clients.txt: add some info about gmail

Signed-off-by: NTim Hockin <thockin@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/email-clients.txt

@@ -213,4 +213,29 @@ TkRat (GUI)
 
 Works.  Use "Insert file..." or external editor.
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Gmail (Web GUI)
+
+If you just have to use Gmail to send patches, it CAN be made to work.  It
+requires a bit of external help, though.
+
+The first problem is that Gmail converts tabs to spaces.  This will
+totally break your patches.  To prevent this, you have to use a different
+editor.  There is a firefox extension called "ViewSourceWith"
+(https://addons.mozilla.org/en-US/firefox/addon/394) which allows you to
+edit any text box in the editor of your choice.  Configure it to launch
+your favorite editor.  When you want to send a patch, use this technique.
+Once you have crafted your messsage + patch, save and exit the editor,
+which should reload the Gmail edit box.  GMAIL WILL PRESERVE THE TABS.
+Hoorah.  Apparently you can cut-n-paste literal tabs, but Gmail will
+convert those to spaces upon sending!
+
+The second problem is that Gmail converts tabs to spaces on replies.  If
+you reply to a patch, don't expect to be able to apply it as a patch.
+
+The last problem is that Gmail will base64-encode any message that has a
+non-ASCII character.  That includes things like European names.  Be aware.
+
+Gmail is not convenient for lkml patches, but CAN be made to work.
+
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