python3 通过163邮箱发邮件，附件都变成了tcmime.xxx.bin了，求解决

describeset

代码如下，网上说好像是编码问题，但还是不知道怎么解决，求大神指导：


# coding: utf-8
#  导入 smtplib 和 MIMEText
import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.mime.multipart import MIMEBase
from email import encoders

# 定义发送列表
mailto_list = ['********@qq.com']
# 设置服务器名称、用户名、密码以及邮件后缀
mail_host = "smtp.163.com"
mail_user = "******@163.com"  # 发件邮箱
mail_pass = "******"  # smtp密码
mail_postfix = "163.com"


# 发送邮件函数
def send_mail(to_list, sub, context):
    me = mail_user + "<" + mail_user + "@" + mail_postfix + ">"
    msg = MIMEMultipart(context)
    # msg = MIMEText(context)
    msg['Subject'] = sub
    msg['From'] = me
    msg['To'] = ",".join(to_list)

    # 附件
    filename = '/Users/******/Desktop/111.txt'
    att = MIMEText(open(filename, 'rb').read(), 'base64', 'utf-8')
    att["Content-Type"] = 'application/octet-stream'
    att["Content-Disposition"] = 'attachment; filename="111.txt"'
    encoders.encode_base64(att)
    msg.attach(att)

    try:
        send_smtp = smtplib.SMTP()
        send_smtp.connect(mail_host)
        send_smtp.login(mail_user, mail_pass)
        send_smtp.sendmail(me, to_list, msg.as_string())
        send_smtp.close()
        return True
    except Exception as e:
        print(str(e))
        return False


if __name__ == '__main__':
    if send_mail(mailto_list, "呵呵哒", "哈哈"):
        print("发送成功")
    else:
        print("发送失败")

SixPy

@wei_Y @无符号整形

思想不惧子弹

大佬我也碰到了类似的问题，现在有思路了吗