When the routing is activated via Settings > Miscellaneous > Hide conversation of other agents agents see only their own conversations and can select the unassigned ones.
Agents menu: displays the agents' menu to assign the active conversation to another agent.
Routing if offline: if the
conversation is archived and the user reopens it in the future by
sending a new message, if the assigned agent in the conversation is
offline, the conversation is assigned to another online if there is at
least one, otherwise to no agent.
View unassigned conversations:
allow agents to view the unassigned conversations, when an agent
replies the conversation is automatically assigned to him and the
conversation is removed in real-time from the admin area of the other
agents. Check this option to enable the manual routing.