ValueError: There may be at most 1 Subject headers in a message
for email in email_list:
msg['To'] = email
server = smtplib.SMTP(host='smtp.gmail.com', port=587)
server.starttls()
server.login("[email protected]", "mypassword")
server.send_message(msg)
server.quit()
del msg['To] <----- Delete the subject of the message to resend.