Nested IMAP folders in Apple Mail

  • Last updated on: 2014-12-30
  • Authored by: Milton Prado

This article provides information about a known issue with Apple Mail and IMAP configurations, referred to as nested folders. When nested folders occur, users see multiple child subfolders labeled INBOX underneath the main Inbox folder (as shown in the following figure). This issue is related to the functionality of Apple Mail and the IMAP protocol. Nested folders with Apple Mail are not specific to the Rackspace Email environment.

The information in this article might help you in resolving the issue with nested folders. If you are unable to correct the issue, we recommend contacting the vendor for full support with Apple Mail.

Change the IMAP prefix

Apple Mail enables users to isolate a folder that is used to sort mail data on the email server through what is known as an IMAP path prefix. By adjusting this prefix, some users have been able to resolve the issue.

You can change the IMAP prefix in the advanced settings of the IMAP mailbox, as follows:

  1. Select Mail > Preferences > Accounts.
  2. Select the IMAP account.
  3. Click the Advanced tab.
  4. Try one or both of the following possible fixes:

    • Change the case of the prefix. For example, change INBOX to Inbox.
    • Add a slash (/) at the end of the prefix - for example, INBOX/ or Inbox/. A slash helps Apple Mail recognize that the path ends in a folder.

Change mailbox behavior

Another suggestion is to adjust mailbox behavior. In the following example, the Trash folder is causing an issue. Try enabling and disabling the Move deleted messages to the Trash mailbox option and the Store deleted messages on the server option.

Reset Apple Mail preferences

You can also try resetting Apple Mail preferences. The IMAP prefix settings are located in the account settings file for Apple Mail. Sometimes a corruption of this file can cause these issues. Try removing this file. Note that removing this file might result in you having to enter your account credentials again, however, your IMAP configuration and all mail will stay in Apple Mail.

You can find the file in the following directory: userName/Library/Containers/

By default, the Library folder (under your username folder) is hidden. To access it, perform the following steps:

  1. Open a new Finder window.

  2. Click Go from the menu bar.

  3. Hold down the Alt/Option key on your keyboard.

  4. Click Library from the list of folders.

You can now navigate to the path where your file is located.

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