Briefly introduce the example of automatic downloading of emails in Python

This article brings you relevant knowledge about Python. It introduces in detail how to use Python language to realize automatic downloading of emails and attachment parsing functions. The sample code in the article is explained in detail. Let’s take a look. Take a look, hope it helps everyone.

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Before we start coding, let’s first understand the three email service protocols ：

1. SMTP protocol

SMTP (Simple Mail Transfer Protocol), which is the simple mail transfer protocol. It is equivalent to a transfer station and sends emails to the client.

2. POP3 Protocol

POP3 (Post Office Protocol 3), the third version of the post office protocol, is the first offline protocol standard for email. This protocol downloads emails to the local computer and does not synchronize with the server. The disadvantage is that it is more likely to lose emails or download the same emails multiple times.

3. IMAP protocol

IMAP (Internet Mail Access Protocol), which is the interactive mail access protocol. This protocol connects to remote mailboxes for direct operation and synchronizes content with the server.

Then introduce the email package

The central component of this package is the "object model" that represents the email message. Applications interact with this package primarily through the object model interface defined in the message submodule. Applications can use this API to ask questions about existing emails, construct new emails, or add or remove email subcomponents that themselves use the same object model interface. That is, following the nature of email messages and their MIME subcomponents, the email object model is a tree structure of all objects that provide the EmailMessage API.

Next, we use specific code to implement the functions of logging in to the email client, downloading emails, and parsing the content of email attachments.

First we need to define an email parsing class, which requires three variables:

1. The imap service address to which the email belongs;

2. Email account;

3. Email password [Note: Different email addresses require different security policies. For example, qq email requires SMS verification to obtain a login authorization code instead of a clear text password to log in to the remote client]

class Email_parse:

    def __init__(self,remote_server_url,email_url,password):
    	# imap服务地址
        self.remote_server_url = remote_server_url
        # 邮箱账号
        self.email_url = email_url
        # 邮箱密码
       self.password = password

Then Define the entry function in the class, log in remotely, and get all the emails on the first page by default. We get the subject of the email and print it out [The encoding of different email subjects may be different, and the binary needs to be transcoded to display correctly]

    def main_parse_Email(self):
        """入口函数，登录imap服务"""
        server = imaplib.IMAP4_SSL(self.remote_server_url, 993)
        server.login(self.email_url, self.password)
        server.select('INBOX')
        status,data = server.search(None,"ALL")
        if status != 'OK':
            raise Exception('read email error')
        emailids = data[0].split()
        mail_counts = len(emailids)
        print("count:",mail_counts)
        # 邮件的遍历是按时间从后往前，这里我们选择最新的一封邮件
        for i in range(mail_counts - 1, mail_counts - 2, -1):
            status, edata = server.fetch(emailids[i], '(RFC822)')
            msg = email.message_from_bytes(edata[0][1])
            #获取邮件主题title
            subject = email.header.decode_header(msg.get('subject'))
            if type(subject[-1][0]) == bytes:
                title = subject[-1][0].decode(str(subject[-1][1]))
            elif type(subject[-1][0]) == str:
                title = subject[-1][0]
            print("title:", title)

Among them, the msg variable saves the body of the email, which will be reused later. To msg and tilt, we will construct a class function to return msg and title.

    def get_email_title(msg):
        subject = email.header.decode_header(msg.get('subject'))
        if type(subject[-1][0]) == bytes:
            title = subject[-1][0].decode(str(subject[-1][1]))
        elif type(subject[-1][0]) == str:
            title = subject[-1][0]
        print("title:", title)
        return title

When parsing the email, we divide it into two parts, the email body [HTML] and the attachment [xlsx, etc.]. If we determine that there is an attachment, we will save it to a fixed path. I won’t go into details about the parsing of the table. Packages such as pandas are enough to handle it.

    def get_att(msg):
        """获取附件并下载"""
        filename = Email_parse.get_email_name(msg)
        for part in msg.walk():
            file_name = part.get_param("name")
            if file_name:
                data = part.get_payload(decode=True)
                if data != None:
                    att_file = open('./src/' + filename, 'wb')
                    att_file.write(data)
                    att_file.close()
                else:
                    pass

For the email body content, we directly parse the html and save the text content directly to the .txt file for easy reading.

    def get_text_from_HTML(msg):
        """获取邮件中的html"""
        filename = Email_parse.get_email_name(msg)
        current_title = Email_parse.get_email_title(msg)
        print("filename:",filename,type(filename))
        for part in msg.walk():
            if not part.is_multipart():
                result = part.get_payload(decode=True)
                result = result.decode('gbk')
                f = open(f'./src/{current_title}.txt','w')
                f.write(result)
                f.close()
                return result

The complete code is as follows:

import email
import imaplib
from email.header import decode_header
import pandas as pd
import datetime


class Email_parse:
    def __init__(self,remote_server_url,email_url,password):
        self.remote_server_url = remote_server_url
        self.email_url = email_url
        self.password = password

    def get_att(msg):
        filename = Email_parse.get_email_name(msg)
        for part in msg.walk():
            file_name = part.get_param("name")
            if file_name:
                data = part.get_payload(decode=True)
                if data != None:
                    att_file = open('./src/' + filename, 'wb')
                    att_file.write(data)
                    att_file.close()
                else:
                    pass

    def get_email_title(msg):
        subject = email.header.decode_header(msg.get('subject'))
        if type(subject[-1][0]) == bytes:
            title = subject[-1][0].decode(str(subject[-1][1]))
        elif type(subject[-1][0]) == str:
            title = subject[-1][0]
        print("title:", title)
        return title


    def get_email_name(msg):
        for part in msg.walk():
            file_name = part.get_param("name")
            if file_name:
                h = email.header.Header(file_name)
                dh = email.header.decode_header(h)
                filename = dh[0][0]
                if dh[0][1]:
                    value, charset = decode_header(str(filename, dh[0][1]))[0]
                    if charset:
                        filename = value.decode(charset)
                        print("附件名称：", filename)
                        return filename


    def main_parse_Email(self):
        server = imaplib.IMAP4_SSL(self.remote_server_url, 993)
        server.login(self.email_url, self.password)
        server.select('INBOX')
        status,data = server.search(None,"ALL")
        if status != 'OK':
            raise Exception('read email error')
        emailids = data[0].split()
        mail_counts = len(emailids)
        print("count:",mail_counts)
        for i in range(mail_counts - 1, mail_counts - 2, -1):
            status, edata = server.fetch(emailids[i], '(RFC822)')
            msg = email.message_from_bytes(edata[0][1])
            subject = email.header.decode_header(msg.get('subject'))
            if type(subject[-1][0]) == bytes:
                title = subject[-1][0].decode(str(subject[-1][1]))
            elif type(subject[-1][0]) == str:
                title = subject[-1][0]
            print("title:", title)
            Email_parse.get_att(msg)
            Email_parse.get_text_from_HTML(msg)


    def get_text_from_HTML(msg):
        filename = Email_parse.get_email_name(msg)
        current_title = Email_parse.get_email_title(msg)
        print("filename:",filename,type(filename))
        for part in msg.walk():
            if not part.is_multipart():
                result = part.get_payload(decode=True)
                result = result.decode('gbk')
                f = open(f'./src/{current_title}.txt','w')
                f.write(result)
                f.close()
                return result

if __name__ == "__main__":
    remote_server_url = 'imap.qq.com'
    email_url = "*********@qq.com"
    password = "**********"
    demo = Email_parse(remote_server_url,email_url,password)
    demo.main_parse_Email()

Running results:

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