When set to True, the message Seen flag is not changed during reading.
def get_peek_mode() -> bool: ... def set_peek_mode(value: bool) -> None: ...
peek_mode = property(get_peek_mode, set_peek_mode)
This property contains a true or false to determine whether or not this message should be seen. When this property is set to True, a "PEEK" option is added to all IMAP FETCH commands sent to the server. An RFC compliant IMAP server should not set the "Seen" flag on the message in this case.