Fixed #7655 -- Added two assertions to mail.py to help people debug a common problem (sending strings instead of lists/tuples for 'to' or 'bcc'). Thanks, guettli

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7864 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/mail.py

@@ -205,10 +205,12 @@ class EmailMessage(object):
         conversions.
         """
         if to:
+            assert not isinstance(to, basestring), '"to" argument must be a list or tuple'
             self.to = list(to)
         else:
             self.to = []
         if bcc:
+            assert not isinstance(bcc, basestring), '"bcc" argument must be a list or tuple'
             self.bcc = list(bcc)
         else:
             self.bcc = []