hgext/notify.py

--- a/hgext/notify.py	Sat Jan 26 10:00:17 2019 -0800
+++ b/hgext/notify.py	Sat Jan 26 10:22:09 2019 -0800
@@ -367,8 +367,12 @@
             raise error.Abort(inst)
 
         # store sender and subject
-        sender = encoding.strtolocal(msg[r'From'])
-        subject = encoding.strtolocal(msg[r'Subject'])
+        sender = msg[r'From']
+        subject = msg[r'Subject']
+        if sender is not None:
+            sender = encoding.strtolocal(sender)
+        if subject is not None:
+            subject = encoding.strtolocal(subject)
         del msg[r'From'], msg[r'Subject']
 
         if not msg.is_multipart():