NDRメールマスク化

import email
from email import policy
from email.parser import BytesParser
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText

# NDRメールのファイルパス
ndr_email_path = 'path/to/ndr_email.eml'

def mask_message_body(ndr_email_path):
    # メッセージをパース
    with open(ndr_email_path, 'rb') as f:
        msg = BytesParser(policy=policy.default).parse(f)
    
    if msg.get_content_type() != 'multipart/report':
        raise ValueError('This is not a multipart/report email')

    # 新しいmultipart/reportメッセージを作成
    multipart_report = MIMEMultipart('report', report_type='delivery-status')
    multipart_report.set_boundary(msg.get_boundary())

    for part in msg.iter_parts():
        content_type = part.get_content_type()

        if content_type == 'text/plain':
            multipart_report.attach(part)
        elif content_type == 'message/delivery-status':
            multipart_report.attach(part)
        elif content_type == 'message/rfc822':
            original_message = part.get_payload(0)
            
            # メッセージヘッダを保持
            headers = original_message.as_string().split('\n\n', 1)[0]
            # 本文をマスク化
            original_body = original_message.get_payload()
            masked_body = 'x' * len(original_body)
            
            # 新しいmessage/rfc822パートを作成
            masked_message = headers + '\n\n' + masked_body
            masked_part = MIMEText(masked_message, 'rfc822')
            masked_part.replace_header('Content-Type', 'message/rfc822')
            
            multipart_report.attach(masked_part)
        else:
            multipart_report.attach(part)

    return multipart_report

masked_email = mask_message_body(ndr_email_path)

# マスク化されたメールをファイルに保存
with open('masked_ndr_email.eml', 'w') as f:
    f.write(masked_email.as_string())

print('Masked NDR email saved to masked_ndr_email.eml')