Releases deleted message space back to OpenVMS RMS for reuse.

    Because your mail file is locked while PURGE/RECLAIM is running,
    you cannot receive new mail. Users attempting to send you
    mail while PURGE/RECLAIM is running receive an error message
    indicating that their message has not been sent successfully. You
    cannot access your own Mail files while a PURGE/RECLAIM command
    is running.