Use Python 3 instead of 3.0.
diff --git a/Doc/library/mailbox.rst b/Doc/library/mailbox.rst
index 7e6f44a..5cdb683 100644
--- a/Doc/library/mailbox.rst
+++ b/Doc/library/mailbox.rst
@@ -1513,7 +1513,7 @@
mailboxes, such as adding or removing message, and do not provide classes to
represent format-specific message properties. For backward compatibility, the
older mailbox classes are still available, but the newer classes should be used
-in preference to them. The old classes will be removed in Python 3.0.
+in preference to them. The old classes will be removed in Python 3.
Older mailbox objects support only iteration and provide a single public method: