diff --git a/stdlib/email/_policybase.pyi b/stdlib/email/_policybase.pyi
new file mode 100644
index 000000000..a3dd61a28
--- /dev/null
+++ b/stdlib/email/_policybase.pyi
@@ -0,0 +1,51 @@
+from abc import ABCMeta, abstractmethod
+from collections.abc import Callable
+from email.errors import MessageDefect
+from email.header import Header
+from email.message import Message
+from typing import Any
+from typing_extensions import Self
+
+class _PolicyBase:
+    def __add__(self, other: Any) -> Self: ...
+    def clone(self, **kw: Any) -> Self: ...
+
+class Policy(_PolicyBase, metaclass=ABCMeta):
+    max_line_length: int | None
+    linesep: str
+    cte_type: str
+    raise_on_defect: bool
+    mangle_from_: bool
+    message_factory: Callable[[Policy], Message] | None
+    def __init__(
+        self,
+        *,
+        max_line_length: int | None = 78,
+        linesep: str = "\n",
+        cte_type: str = "8bit",
+        raise_on_defect: bool = False,
+        mangle_from_: bool = False,
+        message_factory: Callable[[Policy], Message] | None = None,
+    ) -> None: ...
+    def handle_defect(self, obj: Message, defect: MessageDefect) -> None: ...
+    def register_defect(self, obj: Message, defect: MessageDefect) -> None: ...
+    def header_max_count(self, name: str) -> int | None: ...
+    @abstractmethod
+    def header_source_parse(self, sourcelines: list[str]) -> tuple[str, str]: ...
+    @abstractmethod
+    def header_store_parse(self, name: str, value: str) -> tuple[str, str]: ...
+    @abstractmethod
+    def header_fetch_parse(self, name: str, value: str) -> str: ...
+    @abstractmethod
+    def fold(self, name: str, value: str) -> str: ...
+    @abstractmethod
+    def fold_binary(self, name: str, value: str) -> bytes: ...
+
+class Compat32(Policy):
+    def header_source_parse(self, sourcelines: list[str]) -> tuple[str, str]: ...
+    def header_store_parse(self, name: str, value: str) -> tuple[str, str]: ...
+    def header_fetch_parse(self, name: str, value: str) -> str | Header: ...  # type: ignore[override]
+    def fold(self, name: str, value: str) -> str: ...
+    def fold_binary(self, name: str, value: str) -> bytes: ...
+
+compat32: Compat32
diff --git a/stdlib/email/policy.pyi b/stdlib/email/policy.pyi
index 804044031..5f1cf934e 100644
--- a/stdlib/email/policy.pyi
+++ b/stdlib/email/policy.pyi
@@ -1,55 +1,11 @@
-from abc import ABCMeta, abstractmethod
 from collections.abc import Callable
+from email._policybase import Compat32 as Compat32, Policy as Policy, compat32 as compat32
 from email.contentmanager import ContentManager
-from email.errors import MessageDefect
-from email.header import Header
 from email.message import Message
 from typing import Any
-from typing_extensions import Self
 
 __all__ = ["Compat32", "compat32", "Policy", "EmailPolicy", "default", "strict", "SMTP", "HTTP"]
 
-class Policy(metaclass=ABCMeta):
-    max_line_length: int | None
-    linesep: str
-    cte_type: str
-    raise_on_defect: bool
-    mangle_from_: bool
-    message_factory: Callable[[Policy], Message] | None
-    def __init__(
-        self,
-        *,
-        max_line_length: int | None = ...,
-        linesep: str = ...,
-        cte_type: str = ...,
-        raise_on_defect: bool = ...,
-        mangle_from_: bool = ...,
-        message_factory: Callable[[Policy], Message] | None = ...,
-    ) -> None: ...
-    def clone(self, **kw: Any) -> Self: ...
-    def handle_defect(self, obj: Message, defect: MessageDefect) -> None: ...
-    def register_defect(self, obj: Message, defect: MessageDefect) -> None: ...
-    def header_max_count(self, name: str) -> int | None: ...
-    @abstractmethod
-    def header_source_parse(self, sourcelines: list[str]) -> tuple[str, str]: ...
-    @abstractmethod
-    def header_store_parse(self, name: str, value: str) -> tuple[str, str]: ...
-    @abstractmethod
-    def header_fetch_parse(self, name: str, value: str) -> str: ...
-    @abstractmethod
-    def fold(self, name: str, value: str) -> str: ...
-    @abstractmethod
-    def fold_binary(self, name: str, value: str) -> bytes: ...
-
-class Compat32(Policy):
-    def header_source_parse(self, sourcelines: list[str]) -> tuple[str, str]: ...
-    def header_store_parse(self, name: str, value: str) -> tuple[str, str]: ...
-    def header_fetch_parse(self, name: str, value: str) -> str | Header: ...  # type: ignore[override]
-    def fold(self, name: str, value: str) -> str: ...
-    def fold_binary(self, name: str, value: str) -> bytes: ...
-
-compat32: Compat32
-
 class EmailPolicy(Policy):
     utf8: bool
     refold_source: str