使用邮箱访问 mbox 中的所有字段

Question

我正在尝试对 mbox 格式的电子邮件执行一些处理。

经过搜索，尝试了一些试错https://docs.python.org/3/library/mailbox.html#mbox

我已经使用下面列出的测试代码完成了大部分我想做的事情（即使我必须编写代码来解码主题）。

我发现这有点碰运气，特别是查找字段所需的键 'subject' 似乎是反复试验，我似乎找不到任何方法来列出候选人信息。（我知道这些字段可能因电子邮件而异。）

谁能帮我列出可能的值？

我还有一个问题；该电子邮件可能包含多个“已收到：”字段，例如

Received: from awcp066.server-cpanel.com
Received: from mail116-213.us2.msgfocus.com ([185.187.116.213]:60917)
    by awcp066.server-cpanel.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256)

我有兴趣按时间顺序访问第一个 - 我很乐意搜索，但似乎找不到任何方法来访问文件中的第一个。

#! /usr/bin/env python3
#import locale
#2020-08-31

"""
Extract Subject from MBOX file
"""

import os, time
import mailbox
import base64, quopri

def isbqencoded(s):
    """
    Test if Base64 or Quoted Printable strings
    """
    return s.upper().startswith('=?UTF-8?')

def bqdecode(s):
    """
    Convert UTF-8 Base64 or Quoted Printable string to str
    """
    nd = s.find('?=', 10)
    if s.upper().startswith('=?UTF-8?B?'):   # Base64
        bbb = base64.b64decode(s[10:nd])
    elif s.upper().startswith('=?UTF-8?Q?'): # Quoted Printable
        bbb = quopri.decodestring(s[10:nd])
    return bbb.decode("utf-8")

def sdecode(s):
    """
    Convert possibly multiline Base64 or Quoted Printable strings to str
    """
    outstr = ""
    if s is None:
        return outstr
    for ss in str(s).splitlines():   # split multiline strings
        sss = ss.strip()
        for sssp in sss.split(' '):   # split multiple strings
            if isbqencoded(sssp):
                outstr += bqdecode(sssp)
            else:
                outstr += sssp
            outstr+=' '
        outstr = outstr.strip()
    return outstr

INBOX = '~/temp/2020227_mbox'

print('Messages in ', INBOX)
mymail = mailbox.mbox(INBOX)
print('Values = ', mymail.values())
print('Keys = ', mymail.keys())
# print(mymail.items)
# for message in mailbox.mbox(INBOX):
for message in mymail:

#     print(message)
    subject = message['subject']
    to = message['to']
    id = message['id']
    received = message['Received']
    sender = message['from']
    ddate = message['Delivery-date']
    envelope = message['Envelope-to']


    print(sdecode(subject))
    print('To ', to)
    print('Envelope ', envelope)
    print('Received ', received)
    print('Sender ', sender)
    print('Delivery-date ', ddate)
#     print('Received ', received[1])

在的基础上，我简化了Subject解码，得到了类似的结果。

我仍在寻找有关访问 Header 其余部分的建议 - 特别是如何访问多个“已收到：”字段。

#! /usr/bin/env python3
#import locale
#2020-09-02

"""
Extract Subject from MBOX file
"""

import os, time
import mailbox
from email.parser import BytesParser
from email.policy import default

INBOX = '~/temp/2020227_mbox'
print('Messages in ', INBOX)

mymail = mailbox.mbox(INBOX, factory=BytesParser(policy=default).parse)

for _, message in enumerate(mymail):
    print("date:  :", message['date'])
    print("to:    :", message['to'])
    print("from   :", message['from'])
    print("subject:", message['subject'])
    print('Received: ', message['received'])

    print("**************************************")

Answer 1

邮件消息object提供了一个get_all方法returns一个header的所有实例，所以我们可以用它来获取接收到的所有值header.

for header in message.get_all('received'):
    print('Received', header)

每个 header 都是 UnstructuredHeader 的一个实例。这对于识别最早收到的 header 不是很有帮助，因为需要解析 header 以提取日期以便对它们进行排序。

然而，根据 this answer, which quotes the RFC, received headers are always inserted at the beginning of the message. The docstring 对于 EmailMessage.get_all() 的说法：

Return a list of all the values for the named field. These will be sorted in the order they appeared in the original message, and may contain duplicates.

所以最早收到的 header 应该是 EmailMessage.get_all() 返回的列表中的最后一个 header。

Answer 2

根据 snakecharmerb 的评论（现已编辑到问题中）我简化了过程。
最后我不需要解码 received，因为 Message-ID 实际上提取了 id 来自原始的 received 字段。

我列出我最终使用的代码，以防对其他人有用。此代码仅提取 header 个感兴趣的字段并打印它们，但完整代码对消息执行分析。

#! /usr/bin/env python3
#import locale
#2020-09-05

"""
Extract Message Header details from MBOX file
"""

import os, time
import mailbox
from email.parser import BytesParser
from email.policy import default

INBOX = '~/temp/Gmail'

print('Messages in ', INBOX)

mymail = mailbox.mbox(INBOX, factory=BytesParser(policy=default).parse)

for _, message in enumerate(mymail):
    date = message['date']
    to = message['to']
    sender = message['from']
    subject = message['subject']
    messageID = message['Message-ID']
    received = message['received']
    deliveredTo = message['Delivered-To']
    if(messageID == None): continue

    print("Date        :", date)
    print("From        :", sender)
    print("To:         :", to)
    print('Delivered-To:', deliveredTo)
    print("Subject     :", subject)
    print("Message-ID  :", messageID)
#     print('Received    :', received)

    print("**************************************")

使用邮箱访问 mbox 中的所有字段

Access all fields in mbox using mailbox

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