Python smtplib空白消息

import smtplib

smtp_obj = smtplib.SMTP('smtp.example.com', 587)
smtp_obj.starttls()
smtp_obj.login('your_email@example.com', 'your_password')

from email.mime.text import MIMEText
from email.header import Header

subject = '空白消息'
sender = 'your_email@example.com'
receivers = ['recipient1@example.com', 'recipient2@example.com']

message = MIMEText('', 'plain', 'utf-8')
message['Subject'] = Header(subject, 'utf-8')
message['From'] = Header(sender, 'utf-8')
message['To'] = Header(','.join(receivers), 'utf-8')

smtp_obj.sendmail(sender, receivers, message.as_string())
smtp_obj.quit()