2.8 Exception classes

The following exception classes are defined in the email.Errors module:

exception MessageError(): This is the base class for all exceptions that the email package can raise. It is derived from the standard Exception class and defines no additional methods.

exception MessageParseError(): This is the base class for exceptions thrown by the Parser class. It is derived from MessageError.

exception HeaderParseError(): Raised under some error conditions when parsing the RFC 2822 headers of a message, this class is derived from MessageParseError. It can be raised from the Parser.parse() or Parser.parsestr() methods.
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.

exception BoundaryError(): Raised under some error conditions when parsing the RFC 2822 headers of a message, this class is derived from MessageParseError. It can be raised from the Parser.parse() or Parser.parsestr() methods.
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.

exception MultipartConversionError(): Raised when a payload is added to a Message object using add_payload(), but the payload is already a scalar and the message's Content-Type: main type is not either multipart or missing. MultipartConversionError multiply inherits from MessageError and the built-in TypeError.
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).