1 :mod:`email.errors`: Exception and Defect classes
2 -------------------------------------------------
3 
4 .. module:: email.errors
5    :synopsis: The exception classes used by the email package.
6 
7 
8 The following exception classes are defined in the :mod:`email.errors` module:
9 
10 
11 .. exception:: MessageError()
12 
13    This is the base class for all exceptions that the :mod:`email` package can
14    raise.  It is derived from the standard :exc:`Exception` class and defines no
15    additional methods.
16 
17 
18 .. exception:: MessageParseError()
19 
20    This is the base class for exceptions raised by the :class:`~email.parser.Parser`
21    class.  It is derived from :exc:`MessageError`.
22 
23 
24 .. exception:: HeaderParseError()
25 
26    Raised under some error conditions when parsing the :rfc:`2822` headers of a
27    message, this class is derived from :exc:`MessageParseError`. It can be raised
28    from the :meth:`Parser.parse <email.parser.Parser.parse>` or
29    :meth:`Parser.parsestr <email.parser.Parser.parsestr>` methods.
30 
31    Situations where it can be raised include finding an envelope header after the
32    first :rfc:`2822` header of the message, finding a continuation line before the
33    first :rfc:`2822` header is found, or finding a line in the headers which is
34    neither a header or a continuation line.
35 
36 
37 .. exception:: BoundaryError()
38 
39    Raised under some error conditions when parsing the :rfc:`2822` headers of a
40    message, this class is derived from :exc:`MessageParseError`. It can be raised
41    from the :meth:`Parser.parse <email.parser.Parser.parse>` or
42    :meth:`Parser.parsestr <email.parser.Parser.parsestr>` methods.
43 
44    Situations where it can be raised include not being able to find the starting or
45    terminating boundary in a :mimetype:`multipart/\*` message when strict parsing
46    is used.
47 
48 
49 .. exception:: MultipartConversionError()
50 
51    Raised when a payload is added to a :class:`~email.message.Message` object
52    using :meth:`add_payload`, but the payload is already a scalar and the
53    message's :mailheader:`Content-Type` main type is not either
54    :mimetype:`multipart` or missing.  :exc:`MultipartConversionError` multiply
55    inherits from :exc:`MessageError` and the built-in :exc:`TypeError`.
56 
57    Since :meth:`Message.add_payload` is deprecated, this exception is rarely
58    raised in practice.  However the exception may also be raised if the
59    :meth:`~email.message.Message.attach`
60    method is called on an instance of a class derived from
61    :class:`~email.mime.nonmultipart.MIMENonMultipart` (e.g.
62    :class:`~email.mime.image.MIMEImage`).
63 
64 Here's the list of the defects that the :class:`~email.parser.FeedParser`
65 can find while parsing messages.  Note that the defects are added to the message
66 where the problem was found, so for example, if a message nested inside a
67 :mimetype:`multipart/alternative` had a malformed header, that nested message
68 object would have a defect, but the containing messages would not.
69 
70 All defect classes are subclassed from :class:`email.errors.MessageDefect`, but
71 this class is *not* an exception!
72 
73 .. versionadded:: 2.4
74    All the defect classes were added.
75 
76 * :class:`NoBoundaryInMultipartDefect` -- A message claimed to be a multipart,
77   but had no :mimetype:`boundary` parameter.
78 
79 * :class:`StartBoundaryNotFoundDefect` -- The start boundary claimed in the
80   :mailheader:`Content-Type` header was never found.
81 
82 * :class:`FirstHeaderLineIsContinuationDefect` -- The message had a continuation
83   line as its first header line.
84 
85 * :class:`MisplacedEnvelopeHeaderDefect` - A "Unix From" header was found in the
86   middle of a header block.
87 
88 * :class:`MalformedHeaderDefect` -- A header was found that was missing a colon,
89   or was otherwise malformed.
90 
91 * :class:`MultipartInvariantViolationDefect` -- A message claimed to be a
92   :mimetype:`multipart`, but no subparts were found.  Note that when a message
93   has this defect, its :meth:`~email.message.Message.is_multipart` method may
94   return false even though its content type claims to be :mimetype:`multipart`.
95 
96