Python 发送邮件，邮件可以正常接收，但收件人栏显示异常

如题，使用 python 编写了个发送邮件的 Demo 。邮件发送后，用 Foxmail 能够正常收的到。

但是收件人一栏显示的收件邮箱很奇怪，如下图，一整个收件邮箱被按字符拆分为好多个小邮箱，小邮箱的那域名我也没见过。

原本收件邮箱应该显示是 cjcai@zjft.com

不知道有大佬遇到过这种情况没，请教下

下面是源码（看着没毛病）：

# 编译日期：2019-10-14 15:01:36
# coding=utf-8

import os
from email.mime.text import MIMEText
from email.header import Header
from email.mime.multipart import MIMEMultipart
from email.mime.application import MIMEApplication

# 发送邮件（附件）
# email_user: 发件人
# email_pass: 密码
# receivers：收件人列表，例：['xx@zjft.com','xxx@qq.com']
# filepath: 文件地址 如：r'D:\分行查询支行卷别库存 Excel\作文.xlsx'
def sendEmail(email_user, email_pass, receivers, filepath):
    mail_host = '10.10.10.10' # 设置服务器地址
    sender = email_user + '@xxx.com.cn' # 发件人邮箱

    # 创建一个带附件的实例
    message = MIMEMultipart()
    
    # 设置发件人、收件人
    message['From'] = sender
    message['To'] = ", ".join(receivers)
    # 设置邮件主题
    message['Subject'] = Header('查冻扣报备文件', 'utf-8')
    # 邮件正文
    message.attach(MIMEText('查冻扣报备文件已发送，请查看附件！', 'plain', 'utf-8'))

    # 构造附件
    xlsx = MIMEApplication(open(filepath,'rb').read())
    xlsx['Content-Type'] = 'application/octet-stream'
    filename = os.path.basename(filepath)
    xlsx.add_header('Content-Disposition', 'attachment', filename=Header(filename, 'utf-8').encode())
    message.attach(xlsx)

    try:
        smtpObj = smtplib.SMTP(mail_host, 1025)
        smtpObj.login(email_user, email_pass)
        smtpObj.sendmail(sender, receivers, message.as_string())
        print("邮件发送成功，收件人：" + str(receivers) + "\n 附件地址:" + str(filepath))
    except smtplib.SMTPException as e:
        print("邮件发送失败，收件人：" + str(receivers) + "\n 附件地址:" + str(filepath))
        print(e)