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No Valid MBOX Files Were Found on Mac Mail : Resolve the Error

Published By Raj Kumar
Anuraag Singh
Approved By Anuraag Singh
Published On October 28th, 2022
Reading Time 5 Minutes Reading
Category conversion

No valid MBOX files were found

Are you searching for a solution for the pop-up error message “No valid MBOX files were found” on your email account? Then you are at the right place. This blog describes the manual as well as the automated method to resolve it in simple steps. In the following section, you can explore more about the MBOX file and the solution to fix the file error.

In today’s arena, electronic mails are the most commonly used means of communication among people. i.e. email messaging is now used by a large number of individuals and organizations for transferring their personal as well as business information. The different operating system supports different email clients and different file format to store emails. One such common file format used by many operating systems is the MBOX file format.

The MBOX file format is used by various email applications like Mozilla Thunderbird, Eudora, Mulberry, Horde Mail, Chaos Intellect, Entourage, SeaMonkey, Pocomail, Mulberry, Apple Mail, Opera Mail, Netscape Mail, etc. But as we know, there are situations that lead to the corruption of these files. Let us see what are the main reasons that result in causing this error.

No Valid MBOX Files Were Found – Reasons for Causing this Error Message?

Since the MBOX file is saved on computers locally, there are chances for occurring corruption in these files. There can be various causes that result in mailbox file corruption. It can occur due to virus attachment, improper management, sudden termination, etc. And when an application opens this MBOX file, it will generate the error.

Manual Methods to Resolve No Valid MBOX Files Were Found

There are some situations where users get stuck, both situations have one solution which is briefly explained below.

Situation 1:

When a user needs to import .mbox files to an external device from the backup of the old mailbox as MBOX files. Most of the time User clicks on the File >> Import option. He/She tries to transfer one file at a time into the mail. But unexpectedly, a dialogue box displays the error message. Therefore the question arises is how to fix this error to access the MBOX files.

Situation 2:

When a user needs to import a .mbox file from one version of Mac OS to the other, there occur some compatibility issues that generate an error message No valid MBOX files were found. Here, the migration steps from Mac OS 10.6 Snow Leopard to 10.7 Lion are described. The following steps can also be useful for older versions of the operating system.

Solution: Before beginning the migration process, the user has to take a backup of the following:

  • ~/Library/Mail/
  • ~/Library/Preferences/com.apple.mail.plist

Note: If the user needs to open the hidden user’s library folders in the Finder,

Copy ~/Library/ and select Go >> Go to Folder and paste the path>> Go

go to folder option

For migrating the different versions of Mail.app that uses different file formats or database structures, the importing process is done. For that, it is important to have access to old messages that are originally located in the folder:


To Import Different Versions of Mail.app Follow the Steps Given Below:

  • Transfer the Mail Rules: The user needs to copy MessageRules.plist from the old mail folder to the new mail folder ~/Library/Mail/V2/MailData/. And if the MessageRules.plist.backup is there already, then delete it.
  • Now, in the Mail.app and in Preferences, confirm the presence of rules.
  • Start importing MBOX files to Mac Mail.
    • Choose File >> Import Mailboxes >> choose Apple Mail >> Continue.

select apple mail and then continue

If the user wants to import the mailbox files individually in .mbox format and it is returning an error No valid MBOX files were found. Then he/she should try to move the mailboxes instead of transferring the each file separately.

    • Click on Choose >> select the Mail folder from which the user wants to migrate. The user can also preview all the content found in mailboxes at this time.
    • Press the Continue button to begin the process.

select the items to import

    • Now verify and bring everything in order.
  • Close and Open the Mail.app again.
  • Now check the Import Mailbox and move the migrated mailboxes to the correct location.
  • Then check whether the search tool works or not. And if the search tool is not working properly then you have to recreate the SpotLight index with the help of the shell command given:
    sudo mdutil -E /
  • Finally, verify whether the mail rules are present in the Preferences or not.

Also Read: How to export emails Mac mail to Window Outlook

Situation 3:

When a user is moving an MBOX file from an incorrect directory level, then there will be an error message displayed on the screen. Therefore, to overcome this situation, the user needs to shift the directory level by one.

Solution: To resolve this, follow the steps discussed below:

    1. First set the backup directory level by one.
    2. Then select the Mailbox folder from the location given below:


  1. Now you can see a list of MBOX file displayed.
  2. Choose the files that you want to import and then start the process.

If you are looking to export your MBOX files to different email clients like Thunderbird, Outlook, Office 365 etc. We provides you the best MBOX Conversion tool for Mac & Windows hassle free conversion. The main quality of this tool is that it can perform both selective and multiple migrations of files without causing any error. Moreover, the utility also provides a trial version that can be utilized for free before purchasing it.

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Let’s Conclude

The end number of Mac Mail users are having a drought about how to resolve the error no valid MBOX files were found. This blog describes the causes of this error in order to solve it from start. It then suggests different manual approaches based on the different situations.

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