Google App Engine python入站郵件LookupError：未知編碼

Question

按照docs中的示例，我正在使用“標准”入站郵件處理程序接收到我的Google App Engine應用程序的入站電子郵件。

似乎發送給應用程序的某些電子郵件消息（不是我本人造成的）導致電子郵件api拋出LookupError：未知編碼異常。 請參閱回溯。

據我所知，此異常是在調用應用程序的郵件處理程序之前引發的，顯然使它無法被應用程序的代碼捕獲和處理。 真的是這樣嗎？

同樣，App Engine似乎每隔40分鍾重試一次失敗的消息，這會繼續產生錯誤（和警報...），是否有任何方法可以中止此操作？

謝謝你的幫助。

追溯：

Traceback (most recent call last):
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1535, in __call__
    rv = self.handle_exception(request, response, e)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1529, in __call__
    rv = self.router.dispatch(request, response)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1278, in default_dispatcher
    return route.handler_adapter(request, response)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 1102, in __call__
    return handler.dispatch()
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 572, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "/base/data/home/runtimes/python27/python27_lib/versions/third_party/webapp2-2.5.2/webapp2.py", line 570, in dispatch
    return method(*args, **kwargs)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/webapp/mail_handlers.py", line 70, in post
    self.receive(mail.InboundEmailMessage(self.request.body))
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/api/mail.py", line 939, in __init__
    self.update_from_mime_message(mime_message)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/api/mail.py", line 1513, in update_from_mime_message
    super(InboundEmailMessage, self).update_from_mime_message(mime_message)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/api/mail.py", line 1422, in update_from_mime_message
    super(EmailMessage, self).update_from_mime_message(mime_message)
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/api/mail.py", line 1291, in update_from_mime_message
    subject = _decode_and_join_header(mime_message['subject'], separator=u'')
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/api/mail.py", line 597, in _decode_and_join_header
    for s, charset in email.header.decode_header(header))
  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/api/mail.py", line 597, in 
    for s, charset in email.header.decode_header(header))
LookupError: unknown encoding: iso-8859-8-i

Answer 1

調用入站郵件處理程序的post方法時發生錯誤。

  File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/webapp/mail_handlers.py", line 70, in post
    self.receive(mail.InboundEmailMessage(self.request.body))

最簡單的解決方案是在您自己的處理程序中覆蓋post方法以捕獲錯誤：

import logging
from google.appengine.ext.webapp.mail_handlers import InboundMailHandler


class MyInboundMailHandler(InboundMailHandler):

    def post(self):
        try:
            super(MyInboundMailHandler, self).post()
        except LookupError as ex:
            logging.warning('Could not process message because %s.', ex)

    def receive(self, mail_message):
        # Process message

如果您不想丟失該消息，則可以創建並注冊自定義的iso-8859-8-i編解碼器。 這似乎不是一個有據可查的過程，但是這些問題提供了一些提示：

如何正確創建自定義文本編解碼器？

自定義Python Charmap編解碼器

如何在python中編寫自定義編碼以清理數據？

標准庫的iso-8859-8編碼提供了一個很好的模板。