#24218: Add SMTPUTF8 support to send_message.

Reviewed by Maciej Szulik.

1 files changed, 26 insertions, 3 deletions

diff --git a/Lib/smtplib.py b/Lib/smtplib.py
index 6895bed..71ccd2a 100755
--- a/Lib/smtplib.py
+++ b/Lib/smtplib.py
@@ -872,7 +872,13 @@ class SMTP:
         to_addr, any Bcc field (or Resent-Bcc field, when the Message is a
         resent) of the Message object won't be transmitted.  The Message
         object is then serialized using email.generator.BytesGenerator and
-        sendmail is called to transmit the message.
+        sendmail is called to transmit the message.  If the sender or any of
+        the recipient addresses contain non-ASCII and the server advertises the
+        SMTPUTF8 capability, the policy is cloned with utf8 set to True for the
+        serialization, and SMTPUTF8 and BODY=8BITMIME are asserted on the send.
+        If the server does not support SMTPUTF8, an SMPTNotSupported error is
+        raised.  Otherwise the generator is called without modifying the
+        policy.
 
         """
         # 'Resent-Date' is a mandatory field if the Message is resent (RFC 2822
@@ -885,6 +891,7 @@ class SMTP:
         # option allowing the user to enable the heuristics.  (It should be
         # possible to guess correctly almost all of the time.)
 
+        self.ehlo_or_helo_if_needed()
         resent = msg.get_all('Resent-Date')
         if resent is None:
             header_prefix = ''
@@ -900,14 +907,30 @@ class SMTP:
         if to_addrs is None:
             addr_fields = [f for f in (msg[header_prefix + 'To'],
                                        msg[header_prefix + 'Bcc'],
-                                       msg[header_prefix + 'Cc']) if f is not None]
+                                       msg[header_prefix + 'Cc'])
+                           if f is not None]
             to_addrs = [a[1] for a in email.utils.getaddresses(addr_fields)]
         # Make a local copy so we can delete the bcc headers.
         msg_copy = copy.copy(msg)
         del msg_copy['Bcc']
         del msg_copy['Resent-Bcc']
+        international = False
+        try:
+            ''.join([from_addr, *to_addrs]).encode('ascii')
+        except UnicodeEncodeError:
+            if not self.has_extn('smtputf8'):
+                raise SMTPNotSupportedError(
+                    "One or more source or delivery addresses require"
+                    " internationalized email support, but the server"
+                    " does not advertise the required SMTPUTF8 capability")
+            international = True
         with io.BytesIO() as bytesmsg:
-            g = email.generator.BytesGenerator(bytesmsg)
+            if international:
+                g = email.generator.BytesGenerator(
+                    bytesmsg, policy=msg.policy.clone(utf8=True))
+                mail_options += ['SMTPUTF8', 'BODY=8BITMIME']
+            else:
+                g = email.generator.BytesGenerator(bytesmsg)
             g.flatten(msg_copy, linesep='\r\n')
             flatmsg = bytesmsg.getvalue()
         return self.sendmail(from_addr, to_addrs, flatmsg, mail_options,