Delivery Box Troubles: How do they work?

Admittedly this is a minor question, but I wanted to post it just in case the answer might help other people: Do the Delivery Boxes in the Vault (for sending items between your own characters) work? For some reason they seem to be locked out for me, with the fleur de lis symbol marking them as unusable. Or have they always been unaccessible and I just never noticed it?