python中的smtplib.server.sendmail函数引发UnicodeEncodeError：'ascii‘编解码器无法对字符进行编码

import smtplib
from email.mime.text import MIMEText

# 邮件内容
subject = "邮件主题"
content = "邮件内容"

# 创建邮件对象
msg = MIMEText(content, "plain", "utf-8")
msg["Subject"] = subject

# 发件人、收件人和邮件服务器
from_addr = "发件人邮箱"
to_addr = "收件人邮箱"
smtp_server = "邮件服务器地址"
username = "发件人邮箱"
password = "邮箱密码"

try:
    # 连接邮件服务器
    server = smtplib.SMTP(smtp_server)
    server.login(username, password)
    # 发送邮件
    server.sendmail(from_addr, to_addr, msg.as_string())
    # 关闭连接
    server.quit()
    print("邮件发送成功")
except Exception as e:
    print("邮件发送失败:", str(e))