InboxCabin

Freelancers and small-business owners often work across several email accounts. InboxCabin is a Windows desktop app that puts separate inboxes in a sidebar, making them accessible without changing the services that host those mailboxes.

It focuses on account access and switching, rather than combining messages or providing an offline mail archive. The linked InboxCabin guide explains how the workspace works, who it suits, its limitations, and alternatives such as traditional email clients and broader app workspaces.