Retrieves information about messages specified by the MessageSet property.
def fetch_message_info() -> None: ...
This method retrieves information for the messages specified by the message_set property. This includes information about the message envelope as well as message structure. Every time a message envelope is retrieved, a on_message_info event is fired, and message envelope information is stored in properties such as: message_subject, message_from, message_recipients, etc. If the message is a multipart message, one or more on_message_part events are fired before the on_message_info event - one for each message part.