Tests whether a mailbox has contents.
mp
mailbox-not-empty-p mailbox => bool
mailbox
A mailbox
bool
A boolean
The function mailbox-not-empty-p returns nil if the given mailbox is empty and t otherwise.
mailbox-not-empty-p
nil
t
mailbox-count mailbox-empty-p mailbox-send mailbox-peek mailbox-read make-mailbox
LispWorks User Guide and Reference Manual - 21 Dec 2011