Python SMTP学习笔记

SMTP是指简单邮件传输协议（Simple Mail Transfer Protocol），是网络中用于发送电子邮件的标准协议。Python自带了SMTP库，可以方便地发送邮件。

安装SMTP库

Python自带了SMTP库，无需安装。

连接SMTP服务器

在使用SMTP库发送邮件之前，我们需要先连接SMTP服务器。SMTP服务器的地址和端口号与不同的邮件服务提供商有关。以Gmail为例：

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import smtplib

smtp_server = "smtp.gmail.com"
port = 587
smtp_user = "youremail@gmail.com"
smtp_password = "yourpassword"

server = smtplib.SMTP(smtp_server, port)
server.starttls()
server.login(smtp_user, smtp_password)

以上代码会连接到Gmail的SMTP服务器，并使用TLS加密进行通信。其中，smtp_user和smtp_password分别是你的Gmail邮箱地址和密码。

发送邮件

连接SMTP服务器成功后，我们就可以开始发送邮件了。

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

def send_email(sender, receiver, subject, body):
    message = MIMEText(body, 'plain', 'utf-8')
    message['From'] = Header(sender, 'utf-8')
    message['To'] = Header(receiver, 'utf-8')
    message['Subject'] = Header(subject, 'utf-8')

    server.sendmail(sender, [receiver], message.as_string())

send_email('youremail@gmail.com', 'recipientemail@gmail.com', 'Hello from Python!', 'This is a test email sent from Python.')

以上代码会向recipientemail@gmail.com发送一封标题为Hello from Python!的测试邮件。

发送带附件的邮件

除了发送纯文本邮件，SMTP库还可以发送带附件的邮件。

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from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.mime.application import MIMEApplication

def send_email_with_attachment(sender, receiver, subject, body, filepath):
    message = MIMEMultipart()
    message['From'] = Header(sender, 'utf-8')
    message['To'] = Header(receiver, 'utf-8')
    message['Subject'] = Header(subject, 'utf-8')

    # 添加文本内容
    message.attach(MIMEText(body, 'plain', 'utf-8'))

    # 添加附件
    with open(filepath, 'rb') as f:
        attachment = MIMEApplication(f.read(), _subtype=None)
        attachment.add_header('Content-Disposition', 'attachment', filename=filepath.split('/')[-1])
        message.attach(attachment)

    server.sendmail(sender, [receiver], message.as_string())

send_email_with_attachment('youremail@gmail.com', 'recipientemail@gmail.com', 'Email with Attachment', 'This is an email with an attachment sent from Python.', 'path/to/attachment')

以上代码会向recipientemail@gmail.com发送一封标题为Email with Attachment的测试邮件，并附带文件path/to/attachment作为附件。

结束SMTP会话

在结束程序之前，我们需要显式地关闭SMTP会话。

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server.quit()

以上代码会关闭与SMTP服务器的连接。