diff --git a/stdlib/smtpd.pyi b/stdlib/smtpd.pyi
index 5ef11d924..037f62a8d 100644
--- a/stdlib/smtpd.pyi
+++ b/stdlib/smtpd.pyi
@@ -1,10 +1,14 @@
 import asynchat
 import asyncore
 import socket
+import sys
 from collections import defaultdict
 from typing import Any
 
-__all__ = ["SMTPChannel", "SMTPServer", "DebuggingServer", "PureProxy", "MailmanProxy"]
+if sys.version_info >= (3, 11):
+    __all__ = ["SMTPChannel", "SMTPServer", "DebuggingServer", "PureProxy"]
+else:
+    __all__ = ["SMTPChannel", "SMTPServer", "DebuggingServer", "PureProxy", "MailmanProxy"]
 
 _Address = tuple[str, int]  # (host, port)
 
@@ -81,5 +85,6 @@ class DebuggingServer(SMTPServer): ...
 class PureProxy(SMTPServer):
     def process_message(self, peer: _Address, mailfrom: str, rcpttos: list[str], data: bytes | str) -> str | None: ...  # type: ignore[override]
 
-class MailmanProxy(PureProxy):
-    def process_message(self, peer: _Address, mailfrom: str, rcpttos: list[str], data: bytes | str) -> str | None: ...  # type: ignore[override]
+if sys.version_info < (3, 11):
+    class MailmanProxy(PureProxy):
+        def process_message(self, peer: _Address, mailfrom: str, rcpttos: list[str], data: bytes | str) -> str | None: ...  # type: ignore[override]