diff -r 7ac7d5f20cb0 -r bff68b6e5999 mercurial/mail.py
--- a/mercurial/mail.py	Wed Dec 04 20:52:05 2024 -0500
+++ b/mercurial/mail.py	Wed Dec 04 20:53:31 2024 -0500
@@ -28,9 +28,6 @@
 )
 
 from .i18n import _
-from .pycompat import (
-    open,
-)
 from . import (
     encoding,
     error,
@@ -221,7 +218,7 @@
 def _mbox(mbox, sender, recipients, msg):
     '''write mails to mbox'''
     # TODO: use python mbox library for proper locking
-    with open(mbox, b'ab+') as fp:
+    with open(mbox, 'ab+') as fp:
         # Should be time.asctime(), but Windows prints 2-characters day
         # of month instead of one. Make them print the same thing.
         date = time.strftime('%a %b %d %H:%M:%S %Y', time.localtime())
@@ -237,7 +234,7 @@
     """make a mail connection. return a function to send mail.
     call as sendmail(sender, list-of-recipients, msg)."""
     if mbox:
-        open(mbox, b'wb').close()
+        open(mbox, 'wb').close()
         return lambda s, r, m: _mbox(mbox, s, r, m)
     if ui.config(b'email', b'method') == b'smtp':
         return _smtp(ui)