This guide explains how to delete folders that appear grayed out in the Infomaniak Mail web app (online service ksuite.infomaniak.com/mail) or in certain email software/clients such as Apple Mail, Mozilla Thunderbird, or Microsoft Outlook.

Ghost folders

Some email software/clients, such as Microsoft Outlook, allow you to create subfolders of non-existent folders. For example, it is possible to create the folder /abc/klm/xyz even though the folder "klm" does not exist.

In Mail Infomaniak or other software, ghost folders like the folder "klm" appear in gray and cannot be deleted directly because they are only "paths" to a real subfolder.

To delete these ghost folders, you must first delete their subfolders (in this example: xyz).

Stubborn Folders

If, when viewing your Infomaniak email address in Outlook, ghost folders persist or reappear immediately after deletion, here are the technical procedures recommended by Microsoft to force synchronization:

1. Force a reset of the Outlook folders

Sometimes, Outlook's local folder table is corrupted. A simple command can often fix this without deleting anything:

• Close Outlook completely.
• Press the Windows + R keys on your keyboard.
• Type outlook.exe /resetfolders and press Enter (this restores missing or corrupted folders from the server).

2. Reset the IMAP cache (.ost)

If the problem persists, forcing Outlook to rebuild its local database is often the most effective solution:

• Close Outlook.
• Go to the folder: C:\Users\[Your Username]\AppData\Local\Microsoft\Outlook.
• Identify the .ost file with the name of your Infomaniak address and delete it (or rename it to .old for safety).
• Restart Outlook; the software will redownload all your messages and folders cleanly from the Infomaniak servers.

3. Using the MFCMAPI Tool (Advanced Level)

MFCMAPI allows you to directly access the MAPI structure of your mailbox to delete items that the standard Outlook interface refuses to touch:

• Download the latest version of MFCMAPI from GitHub (Official source).
• Launch MFCMAPI.exe and go to Session > Logon; select your Outlook profile.
• Double-click on your Infomaniak email account in the list.
• In the new window, expand Root Container (or Racine - Boîte aux lettres), then IPM_SUBTREE.
• Locate the problematic folder, right-click on it, and select Delete folder.
• Warning: In the dialog box, first try a simple deletion; if that fails, try again by checking DELETE_HARD_DELETE (permanent deletion at the server level).

4. Final check via Webmail

If a folder is deleted in Outlook but keeps reappearing, be sure to check in the Infomaniak Mail web app to see if the folder is present there, and first delete it via the web interface before applying step #1 (resetfolders) in Outlook.