Hiya fr0hzn.
For meshes you need to navigate a path from you hotspots to mailbox you're looking to use.
For profiles you need to add:
<Mailboxes>
<Mailbox X="4599.003" Y="-4233.57" Z="178.6539" />
</Mailboxes>
You can get position (x,y,z) for mailbox using current position when standing at mailbox.
-botter-