Thinking more...

如果你使用 Python smtplib.py 寄信時，遇到認證錯誤訊息(Authentication error)，不妨試試改變一下認證的順序，請在 smtplib.py 裡面找

        # List of authentication methods we support: from preferred to
        # less preferred methods. Except for the purpose of testing the weaker
        # ones, we prefer stronger methods like CRAM-MD5:
        preferred_auths = [AUTH_CRAM_MD5, AUTH_PLAIN, AUTH_LOGIN]

然後修改一下順序，

        preferred_auths = [AUTH_LOGIN, AUTH_CRAM_MD5, AUTH_PLAIN]

或許就能迎刃而解。