[PATCH] Upstream patch - 25062023

addons/mail/models/mail_thread.py

@@ -1286,6 +1286,10 @@ class MailThread(models.AbstractModel):
                     continue  # skip container
 
                 filename = part.get_filename()  # I may not properly handle all charsets
+                if part.get_content_type() == 'text/xml' and not part.get_param('charset'):
+                    # for text/xml with omitted charset, the charset is assumed to be ASCII by the `email` module
+                    # although the payload might be in UTF8
+                    part.set_charset('utf-8')
                 encoding = part.get_content_charset()  # None if attachment
 
                 content = part.get_content()