Cant attach csv file with UTF-8#189

Hello, I attach csv file with unicode string and send to email with postmark. When I download csv file and open with ms excel the file show wrong string. Not sure what I do wrong ? ``` files = [] csvfile = StringIO() writer = csv.writer(csvfile) writer.writerow(['some unicode string']) data = csvfile.getvalue() attachment = MIMEBase('text', 'csv') attachment.set_payload(data.encode('utf-8')) encoders.encode_base64(attachment) attachment.add_header('Content-Disposition', 'attachment', filename='readme.csv') files.append(attachment) email = postmark.emails.send_with_template( TemplateId=xxx, TemplateModel={}, From='[email protected]', To=['[email protected]'], Attachments=files ) ```