Tip: If you want to organize messages without moving them around, account.
If you choose an existing mailbox as the location, the new mailbox is created within the existing mailbox—like a subfolder.
Type a name for the mailbox, then click OK.
In a work environment, public read-only mailboxes may be available in your email account. For example, a public folder may be used to provide information for all users of a company email system. You can’t create mailboxes within or save messages to these read-only mailboxes. To find out how to post messages to the mailbox, ask your email administrator.
To reorder the mailboxes for an email account in the IMAP account, contact the provider of your account.
When you delete a Rename mailboxes in Mail on MacRebuild mailboxes in Mail on Mac