How to Fix “No Valid MBOX File Found” Error on Mac Mail in Simplest Way?

Admin | Email Conversion How to's Software Technology | 5 minutes read | Last updated on February 8th, 2023,

Are you looking for a method for the popped-up error message i.e. “No valid MBOX file found” on your email profile? So, here you are in the right place. This article will help you out it finding the most reliable method to resolve “No valid MBOX file found” error on Mac Mail in the simplest way. Here we described the manual method as same as the professional method to fix the error. In the next section, you can learn more about the MBOX file and technique to solve the file error.

In today’s digital world, electronic emails are one of the most generally used means of communication among people such as email messaging is now used by a large number of individuals and organizations for moving there personal as same as business information. The different operating system supports various email applications and many file format to store the emails. One such common file format used by multiple operating systems is MBOX file format.

The MBOX format is used by numerous email clients like Mozilla Thunderbird, SeaMonkey, Eudora, Apple Mail, Entourage, Pocomail, Opera Mail, Horde Mail, Netscape Mail, The bat! etc. But as we know, there are different situations that lead to the corruption of these files. Let us see, what are the main cause which results in initiating the error no valid MBOX files were found.

Reasons for Initiating this Error Message

When the MBOX file is saved on PC locally, there are great chances for happening corruption in these files. There can be multiple reasons that result in mailbox file corruption. It can happen because of virus attachment, unsuitable management, unexpected termination, etc. And when the application opens this MBOX file, it will create the error.

Manual Solution to Fix “No Valid MBOX Files Were Found” Error

Situation 1.

When a user requires to export .mbox files to the external device from the backup of the old mailbox as MBOX files. Most times the user clicks on the File >> Import option. He/She tries to migrate one file at once into the mail. But suddenly, a pop-up box appears the error message. So the question comes is how to resolve “No valid MBOX file found” error to access the MBOX files?

Solution: The user has to follow the steps described in the next situation to export the MBOX file.

Situation 2.

When a user wants to move .mbox file from one version of Mac OS to another, there happens few compatibility difficulties that creates error message such as No valid MBOX files were found. Here the conversion steps from Mac OS 10.6 Snow Leopard to the 10.7 Lion is given. The following steps can also be useful for older editions of the operating system.


Before initiation of the conversion procedure, a user must take a backup of the following:

  • ~Library/Mail/
  • ~Library/Preferences/

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

Copy ~/Library/ and choose Go >> Go to Folder and paste the location >> Go

For moving the different version of that uses multiple file-formats or the database structure, the exporting process is finished. For that, it is necessary to have access to old messages that are actually located in the folder.


To Move Various Versions of Follow the Steps Provided Below:

  1. Transfer the Mail Rules: The users require 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.
  2. After that, in the and in Preferences, check the existence of rules.
  3. Initiate moving the MBOX files of Mac Mail.

a). Select File >> Import Mailboxes >> select Apple Mail >> Continue.

If the user needs to migrate the mailbox files separately in .mbox file format and it is recurring an error No valid MBOX files were found. Moreover, he/she should try to import the mailboxes in place of moving each file individually.

b). Press on Choose >> choose the Mail folder from which a user needs to export. A user can also preview all the content found in mailboxes at this time.

c). Click on the Continue to start the process.

d). Now verify and carry everything in the order.

  1. Close and Open the again.
  2. Check the Import Mailbox and transfer the exported mailboxes to the correct location.
  3. After that check whether the search tool works or not. And if the search tool is not working perfectly then you must recreate SpotLigh index with the help of the shell command provided:

sudo mdutil –E /

  1. Lastly, verify the mail rules are available in the Preferences or not.

Situation 3.

When a user is transferring MBOX file from the incorrect direction level, then there will be the error message occurred on the screen. Therefore, to fix this situation, the user has to shift the directory level by one.

Solution: To overcome this, follow the below-mentioned steps:

  1. First of all, set the backup directly level by one.
  2. After that, choose the Mailbox folder from the location provided below:


  1. Now you can view the list of MBOX file appeared.
  2. Select the files that you wish to move and then start the procedure.

MBOX Converter – An Automated Solution to Deal with This Error

The manual techniques discussed above to solve the error is a little bit tricky and lengthy. So, to ease this procedure, one can use the professional approach i.e. MBOX Converter. The tool will help you to fix all the difficulties related to the .mbox file and its errors. The major quality of this program is that it can achieve both selective and batch migrations of MBOX files without generating any error.

The Concluding Words

Mostly Apple Mail users are examining about how to fix the error “no valid MBOX files were found”. This article describes the reasons for this error in-order to resolve it from start. Then it recommends various manual methods based on multiple situations. But the manual techniques are very time-taking and problematic. Therefore to simplify the process, here recommends a third-party automated tool that is MBOX Converter. This program is suitable for resolving all the errors related to the .mbox file. Furthermore, the software also gives a free demo edition that can be easily utilized for free before buying it.