The following exception classes are defined in the email.Errors module:
Situations where it can be raised include finding an envelope header after the first RFC 2822 header of the message, finding a continuation line before the first RFC 2822 header is found, or finding a line in the headers which is neither a header or a continuation line.
Situations where it can be raised include not being able to find the starting or terminating boundary in a multipart/* message when strict parsing is used.
Since Message.add_payload() is deprecated, this exception is rarely raised in practice. However the exception may also be raised if the attach() method is called on an instance of a class derived from MIMENonMultipart (e.g. MIMEImage).
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