The UIDValidity parameter sent from the server in response to SelectMailbox command.
def get_uid_validity() -> str: ...
uid_validity = property(get_uid_validity, None)
Every time a mailbox is selected a uid_validity is returned from the server. Most of the time this value will not change from call to call. In case it does change, it means that all previously returned UIDs for messages inside this mailbox are now invalid.
This property is read-only.