Add pluggable transport registry

django_mailbox/transports/__init__.py

@@ -7,4 +7,4 @@ from django_mailbox.transports.mbox import MboxTransport
 from django_mailbox.transports.babyl import BabylTransport
 from django_mailbox.transports.mh import MHTransport
 from django_mailbox.transports.mmdf import MMDFTransport
-from django_mailbox.transports.gmail import GmailImapTransport
+from django_mailbox.transports.gmail import GmailImapTransport

django_mailbox/transports/base.py

@@ -17,3 +17,10 @@ class EmailTransport(object):
             message = email.message_from_string(contents)
 
         return message
+
+
+class PluggableEmailTransport(EmailTransport):
+    @classmethod
+    def from_uri(cls, uri):
+        raise NotImplemented("The class does not implement {0}.from_uri, and it should. "
+                             "Overwrite {0}.from_uri.".format(cls.__name__))

django_mailbox/transports/registry.py

@@ -0,0 +1,8 @@
+transport_registry = {}
+
+
+def register_transport(transport_type):
+    def decorator(f):
+        transport_registry[transport_type] = f
+        return f
+    return decorator