python3发送html格式的邮件

def send_mail(to_list, sub, content, attpath):
    me = "*******" + "<" + mail_user + "@" + mail_postfix + ">"
    msg = MIMEMultipart()
    msg['Subject'] = sub
    msg['From'] = me
    msg['To'] = ";".join(to_list)

    htmlf=open(attpath,'r',encoding="utf-8")
    htmlcont=htmlf.read()

    email_text = MIMEText(htmlcont, _subtype='html')
    msg.attach(email_text)
    sep = os.sep
    attname = attpath.split(sep)[-]
    # 首先是xlsx类型的附件
    email_att = MIMEApplication(open(attpath, 'rb').read())
    email_att.add_header('Content-Disposition', 'attachment', filename=attname)
    msg.attach(email_att)
    try:
        server = smtplib.SMTP()
        server.connect(mail_host)  # 连接服务器
        server.login(mail_user, mail_pass)  # 登录操作
        server.sendmail(me, to_list, msg.as_string())
        server.close()
        return True
    except BaseException:
        return False

关键是加入

_subtype='html'，如果是普通文本，就是plain,