diff --git a/stdlib/2and3/asynchat.pyi b/stdlib/2and3/asynchat.pyi
index d397b4c24..44e1f8349 100644
--- a/stdlib/2and3/asynchat.pyi
+++ b/stdlib/2and3/asynchat.pyi
@@ -9,13 +9,13 @@ class simple_producer:
     def __init__(self, data: str, buffer_size: int = ...) -> None: ...
     def more(self) -> str: ...
 
-class async_chat (asyncore.dispatcher):
+class async_chat(asyncore.dispatcher):
     ac_in_buffer_size = ...  # type: int
     ac_out_buffer_size = ...  # type: int
     def __init__(self, sock: socket.socket = None, map: asyncore._maptype = None) -> None: ...
 
     @abstractmethod
-    def collect_incoming_data(self, data: str) -> None: ...
+    def collect_incoming_data(self, data: bytes) -> None: ...
     @abstractmethod
     def found_terminator(self) -> None: ...
     def set_terminator(self, term: Union[str, int, None]) -> None: ...
diff --git a/stdlib/2and3/smtpd.pyi b/stdlib/2and3/smtpd.pyi
new file mode 100644
index 000000000..f4339c0e5
--- /dev/null
+++ b/stdlib/2and3/smtpd.pyi
@@ -0,0 +1,87 @@
+# Stubs for smtpd (Python 2 and 3)
+import sys
+import socket
+import asyncore
+import asynchat
+
+from typing import Any, DefaultDict, List, Optional, Text, Tuple, Type
+
+_Address = Tuple[str, int]  # (host, port)
+
+
+class SMTPChannel(asynchat.async_chat):
+    COMMAND: int
+    DATA: int
+
+    if sys.version_info >= (3, 3):
+        command_size_limits: DefaultDict[str, int]
+
+    if sys.version_info >= (3,):
+        smtp_server: SMTPServer
+        conn: socket.socket
+        addr: Any
+        received_lines: List[Text]
+        smtp_state: int
+        seen_greeting: str
+        mailfrom: str
+        rcpttos: List[str]
+        received_data: str
+        fqdn: str
+        peer: str
+
+        command_size_limit: int
+        data_size_limit: int
+
+    if sys.version_info >= (3, 5):
+        enable_SMTPUTF8: bool
+
+    if sys.version_info >= (3, 3):
+        @property
+        def max_command_size_limit(self) -> int: ...
+
+    if sys.version_info >= (3, 5):
+        def __init__(self, server: SMTPServer, conn: socket.socket, addr: Any, data_size_limit: int = ...,
+                     map: Optional[asyncore._maptype] = ..., enable_SMTPUTF8: bool = ..., decode_data: bool = ...) -> None: ...
+    elif sys.version_info >= (3, 4):
+        def __init__(self, server: SMTPServer, conn: socket.socket, addr: Any, data_size_limit: int = ...,
+                     map: Optional[asyncore._maptype] = ...) -> None: ...
+    else:
+        def __init__(self, server: SMTPServer, conn: socket.socket, addr: Any, data_size_limit: int = ...) -> None: ...
+    def push(self, msg: Text) -> None: ...
+    def collect_incoming_data(self, data: bytes) -> None: ...
+    def found_terminator(self) -> None: ...
+    def smtp_HELO(self, arg: str) -> None: ...
+    def smtp_NOOP(self, arg: str) -> None: ...
+    def smtp_QUIT(self, arg: str) -> None: ...
+    def smtp_MAIL(self, arg: str) -> None: ...
+    def smtp_RCPT(self, arg: str) -> None: ...
+    def smtp_RSET(self, arg: str) -> None: ...
+    def smtp_DATA(self, arg: str) -> None: ...
+    if sys.version_info >= (3, 3):
+        def smtp_EHLO(self, arg: str) -> None: ...
+        def smtp_HELP(self, arg: str) -> None: ...
+        def smtp_VRFY(self, arg: str) -> None: ...
+        def smtp_EXPN(self, arg: str) -> None: ...
+
+class SMTPServer(asyncore.dispatcher):
+    channel_class: Type[SMTPChannel]
+
+    data_size_limit: int
+    enable_SMTPUTF8: bool
+
+    if sys.version_info >= (3, 5):
+        def __init__(self, localaddr: _Address, remoteaddr: _Address,
+                     data_size_limit: int = ..., map: Optional[asyncore._maptype] = ...,
+                     enable_SMTPUTF8: bool = ..., decode_data: bool = ...) -> None: ...
+    elif sys.version_info >= (3, 4):
+        def __init__(self, localaddr: _Address, remoteaddr: _Address,
+                     data_size_limit: int = ..., map: Optional[asyncore._maptype] = ...) -> None: ...
+    else:
+        def __init__(self, localaddr: _Address, remoteaddr: _Address,
+                     data_size_limit: int = ...) -> None: ...
+    def handle_accepted(self, conn: socket.socket, addr: Any) -> None: ...
+    def process_message(self, peer: _Address, mailfrom: str, rcpttos: List[Text], data: str, **kwargs: Any) -> Optional[str]: ...
+
+class DebuggingServer(SMTPServer): ...
+class PureProxy(SMTPServer): ...
+class MailmanProxy(PureProxy): ...