I used the Buddypress Message Compose to send a site wide email to all members wasnt sent tho [closed]

The way the feature works is by posting the message on the screen, not in the members inbox, and it requires the template tag:

<?php bp_message_get_notices(); ?>

So wherever you put the tag, the message will appear there. In the default buddypress theme, it shows up when you activate a message and the user is logged in, right below the log out link in the sidebar login form.

To send inbox messages through buddypress, you can search for the Mass Messaging plugin.