通过crontab运行时，脚本不会通过邮件给出结果

import smtplib
from email.mime.text import MIMEText

def send_email(subject, content, sender, receiver, smtp_server, smtp_port, username, password):
    msg = MIMEText(content)
    msg['Subject'] = subject
    msg['From'] = sender
    msg['To'] = receiver

    try:
        server = smtplib.SMTP(smtp_server, smtp_port)
        server.starttls()
        server.login(username, password)
        server.sendmail(sender, receiver, 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))

# 在脚本执行完毕后调用send_email函数发送邮件
send_email("脚本执行结果", "脚本执行成功！", "sender@example.com", "receiver@example.com", "smtp.example.com", 587, "username", "password")