只有当代码不在函数或类中时，才能使用smtplib向mailtrap发送电子邮件

Question

这个问题与python: sending a mail, fails when inside a "with" block有些相似。

我正在使用Python (3.6)向mailtrap发送电子邮件。Mailtrap实际上为您提供了smtplib的集成代码，如下所示：

import smtplib

sender = "Private Person <from@smtp.mailtrap.io>"
receiver = "A Test User <to@smtp.mailtrap.io>"

message = f"""\
Subject: Hi Mailtrap
To: {receiver}
From: {sender}

This is a test e-mail message."""

with smtplib.SMTP("smtp.mailtrap.io", 2525) as server:
    server.login("<MYUSER>", "<MYPASSWORD>")
    server.sendmail(sender, receiver, message)

如果我将上面的代码放在一个模块中并运行它，上面的代码就可以正常工作。我转到mailtrap并验证电子邮件是否在那里。但是，我想将其封装在如下的函数中：

import smtplib
from socket import gaierror


def test():
    sender = "Test Dev <from@smtp.mailtrap.io>"
    receiver = "Test User <to@smtp.mailtrap.io>"
    message = f"""\
    Subject: Hi there
    To: {receiver}
    From: {sender}

    TESTING"""

    try:
        with smtplib.SMTP("smtp.mailtrap.io", 2525) as server:
            server.login("<MYUSER>", "<MYPASSWORD")
            print("Sending email")
            server.sendmail(sender, receiver, message)
        print('Sent')


    except (gaierror, ConnectionRefusedError):
        print('Failed to connect to the server. Bad connection settings?')
    except smtplib.SMTPServerDisconnected:
        print('Failed to connect to the server. Wrong user/password?')
    except smtplib.SMTPException as e:
        print('SMTP error occurred: ' + str(e))

if __name__ == "__main__":
    test()

这不管用。为什么？下面是输出：output image没有连接错误或任何其他异常。然而，我去了mailtrap，在那里找不到电子邮件。

这是一个邮件陷阱问题，还是与smtplib有关？我为这件事绞尽脑汁

Answer 1

我也有同样的问题，我不能理解它。我确实注意到，当我将消息设为空字符串时，它起作用了。

经过令人尴尬的长时间搜索后，我找到了这个post，它为我指明了解决方案。

您必须设置电子邮件的MIME类型。因此，不只是传递一个字符串，而是传递一个消息对象：

message = MIMEText("TEST!")
    message["Subject"] = "Alert!"
    message["From"] = sender
    message["To"] = receiver

..。然后最终

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

我的完整发送电子邮件功能如下所示：

    def send_mail(self):
    message = MIMEText("TEST!")
    message["Subject"] = "Alert!"
    message["From"] = sender
    message["To"] = receiver
    try:
        context = ssl.create_default_context()

        with smtplib.SMTP(smtp_server, port) as server:
            server.set_debuglevel(1)
            server.ehlo()  # Can be omitted
            server.starttls(context=context)
            server.ehlo()  # Can be omitted
            server.login(login, password)
            server.sendmail(sender, receiver, message.as_string())
        print('Sent')
    except (gaierror, ConnectionRefusedError):
        print('Failed to connect to the server. Bad connection settings?')
    except smtplib.SMTPServerDisconnected:
        print('Failed to connect to the server. Wrong user/password?')
    except smtplib.SMTPException as e:
        print('SMTP error occurred: ' + str(e))
    except Exception as e:
        print('everything else')

不幸的是，您必须在message对象和sendemail函数中指定发送者和接收者。