diff -r a1801ee97840 -r 54b06bec8914 mercurial/mail.py
--- a/mercurial/mail.py	Thu Oct 10 21:05:34 2019 +0200
+++ b/mercurial/mail.py	Thu Oct 10 21:30:44 2019 +0200
@@ -61,7 +61,7 @@
                 ui=self._ui,
                 serverhostname=self._host,
             )
-            self.file = smtplib.SSLFakeFile(self.sock)
+            self.file = self.sock.makefile("rb")
             self.helo_resp = None
             self.ehlo_resp = None
             self.esmtp_features = {}