2.4 Getting mail

In order for mu (and, by extension, mu4e) to work, you need to have your e-mail messages stored in a Maildir; in this manual we use the term ‘maildir’ for both the standard and the hierarchy of maildirs that store your messages — a specific directory structure with one-file-per-message.

If you are already using a maildir, you are lucky. If not, some setup is required:

While a mu only supports a single Maildir, it can be spread across different file-systems; and symbolic links are supported.