Improve email encoding

hedgedoc-expire.py

@@ -229,10 +229,12 @@ class HedgedocExpire:
                         
                         The admin team for {self.config.url}
                         
-                        ''')))
-                    md = MIMEBase('text', 'markdown')
-                    md.add_header('Content-Disposition', f'attachment; filename={note["title"]}.md')
-                    md.set_payload(note["content"].encode(encoding='utf-8'))
+                        '''), 'plain', 'utf-8'))
+                    md = MIMEText(note["content"], 'markdown', 'utf-8')
+                    filename = note['title'].encode('ascii', 'ignore').decode('utf-8')
+                    if len(filename) == 0:
+                        filename = 'note'
+                    md.add_header('Content-Disposition', f'attachment; filename={filename}.md')
                     msg.attach(md)
                     self.email_sender.send(msg)