How to Resolve the “Impossible to Import in This Folder (IMAP or Newsgroup Type)” Error When Importing MBOX Files

Ritu Roy | File Repair fix How to's Software | 4 minutes read | Modified on: 27-03-2025

Email clients frequently need to import MBOX files, especially when users are backing up their emails or switching email systems. Nevertheless, you can run into the problem notice, “Impossible to import in this folder (IMAP or newsgroup type).” Usually, this notice appears when an MBOX file is attempted to be imported into a folder that is incompatible with such imports, such as a newsgroup or IMAP folder. This post will describe the reasons behind this and offer fixes for the problem.

Understanding MBOX Files and Email Folders

Let’s go over some important ideas before getting into the mistakes and fixes.

• MBOX Format: MBOX is a standard file format used for storing email messages. It is commonly used by many email clients, including Mozilla Thunderbird and Apple Mail, for storing large volumes of email messages in a single file.
• IMAP Folders: Internet Message Access Protocol (IMAP) is a protocol used by email servers to store and manage email messages. IMAP folders are synchronized with the server, meaning that any changes made on your local device (such as reading, deleting, or moving messages) are reflected on the server, and vice versa.
• Newsgroup Folders: These are similar to IMAP folders but are used for Usenet newsgroups, not email. Newsgroup folders often have different configurations and cannot be used for importing regular email messages.

Why the Error Occurs When Importing MBOX Files

You’re trying to import an MBOX file into a folder that is incompatible with IMAP or newsgroup, according to the error message you’re seeing. The purpose of these kinds of folders is to hold real-time newsgroup or email messages that are synchronized with a server directly. Due to their reliance on server syncing rather than local storage, these folders do not allow the direct import of bulk email files such as MBOX.

• IMAP Folders: These folders are synchronized with an email server, and the server itself frequently dictates their content and structure. Therefore, manually importing emails into these folders may cause issues or interfere with the syncing process.
• Newsgroup Folders: The purpose of these folders is to read and post messages on Usenet groups. Furthermore, they are unable to import emails from MBOX files.

Therefore, the “Impossible to import” warning may appear when you try to import an MBOX file into one of these folders.

Solutions to Resolve the Error: Impossible to Import in This Folder

To successfully import an MBOX file, follow these steps:

1. Create a Local Folder for Import

Instead of syncing with an email server, the simplest way is to import the MBOX file into a local folder that is kept on your device. Local folders may simply manage the import process and are not subject to the same restrictions as IMAP or newsgroup folders.

• Thunderbird: In the left sidebar, right-click on the name of your account. Choose New Folder and make sure it’s a local folder. Once the folder has been created, attempt to import the MBOX file into it.
• Outlook: Import the MBOX file into a PST (Personal Storage Table) file, which serves as a local storage folder.
• Apple Mail: Go to File > New Mailbox, and create a new On My Mac folder for importing your MBOX file.

2. Move Emails to IMAP After Importing

If the emails must be in an IMAP folder (for example, to sync with the server on several devices), you can:

1. Import the MBOX file into a local folder.
2. Once the import is complete, manually transfer the emails from the local folder to your IMAP folder. Emails can be easily moved between local and IMAP folders using a variety of email clients.

3. Check for Folder Permissions

In certain situations, the import of files may be restricted by folder rights or settings. Make sure there are no new content restrictions in the folder you are attempting to import the MBOX file into. Look at the folder’s settings, particularly if a server is in charge of it.

4. Consider Splitting Large MBOX Files

The import process can occasionally encounter problems with large MBOX files. If your MBOX file is really big (more than a few gigabytes), it might be beneficial to use a third-party MBOX splitting program to divide it into smaller parts. Smaller files are easier for your email client to process and are less likely to cause import issues.

5. Verify MBOX File Integrity

When importing, corrupt MBOX files can cause problems. Before trying to import it again, you might need to fix the corrupted MBOX file.

Steps to Import MBOX Files into Multiple Email Clients

Here’s a quick guide on how to import MBOX files into different email clients.

In Mozilla Thunderbird:

1. Create a local folder by right-clicking on your email account in the left sidebar and selecting New Folder.
2. Select Local Folders as the location.
3. Once the folder is created, go to Tools > Import, select Mail, and choose MBOX File.
4. Navigate to the location of the MBOX file and import it.

Microsoft Outlook:

1. Create a PST file by going to File > Account Settings > Account Settings > Data Files and selecting Add to create a new PST file.
2. Import the MBOX file using third-party tools like CubexSoft MBOX to PST Converter.

In Apple Mail:

1. Create a local mailbox by going to Mailbox > New Mailbox and selecting On My Mac.
2. Import the MBOX file using File > Import Mailboxes and selecting the MBOX file.

Conclusion

When trying to import MBOX files into incompatible folders, the error “Impossible to import in this folder (IMAP or newsgroup type)” appears. By following the solutions outlined above, creating a local folder, manually moving emails to an IMAP folder after import, and checking file integrity, you should be able to resolve the issue and successfully import your MBOX files.

If you continue to face issues, consider reaching out to the support team of your email client for additional help.