Python smtplib无法附加多个mimetext

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

# 创建包含多个mimetext的消息体
msg = MIMEMultipart()

# 添加文本内容
text1 = MIMEText('This is the first text', 'plain')
msg.attach(text1)

# 添加第二个文本内容
text2 = MIMEText('This is the second text', 'plain')
msg.attach(text2)

# 设置其他邮件头信息
msg['Subject'] = 'Multiple MimeText Example'
msg['From'] = 'sender@example.com'
msg['To'] = 'recipient@example.com'

# 发送邮件
try:
    server = smtplib.SMTP('smtp.example.com', 587)  # 邮件服务器地址和端口号
    server.login('username', 'password')  # 邮件服务器的用户名和密码
    server.sendmail('sender@example.com', 'recipient@example.com', msg.as_string())
    server.quit()
    print("邮件发送成功")
except Exception as e:
    print("邮件发送失败：" + str(e))