#3540: fix exception name.
diff --git a/Doc/library/mailbox.rst b/Doc/library/mailbox.rst
index 79fe72f..0a8c6df 100644
--- a/Doc/library/mailbox.rst
+++ b/Doc/library/mailbox.rst
@@ -1482,7 +1482,7 @@
    parameter set to ``False``), or when opening a folder that does not exist.
 
 
-.. exception:: NotEmptyErrorError()
+.. exception:: NotEmptyError()
 
    Raised when a mailbox is not empty but is expected to be, such as when deleting
    a folder that contains messages.