When there are hundreds or thousands of MBOX emails to move into Outlook, converting each mailbox separately can quickly become a tedious job. The important part is finding a converter that can handle multiple MBOX files in one run and gives you control over how the resulting PST files are created.

Before starting a bulk migration, I would check these points:

Multiple MBOX files: The software should allow several MBOX files to be selected together.

PST organization: Check whether you can merge multiple MBOX files into one PST or create a separate PST for each mailbox.

Selective migration: Being able to choose particular MBOX files is useful when the archive contains mailboxes that do not need to be transferred.

Mailbox data: Check what the conversion carries over, including folders, emails and their properties.

Output review: Always open the converted PST in Outlook and inspect a few folders and messages before converting the complete collection.

If I were to migrate MBOX files in bulk, I would consider GainTools MBOX to PST Converter. The software allows batch selection, enables you to generate one PST from multiple MBOX files or separate PST files and provides a trial that will convert 10 emails from each MBOX. This allows us to test some real archive files before transferring the entire collection.

If it is a large mailbox archive, I would run the trial first, check the resulting PST in Outlook and then proceed to full migration if the output matches the expected mailbox structure.

If you have a lot of EML files and want them all in one Outlook PST, you don’t need to convert each file separately. The easier approach is to add the EML files together and create a single PST from them.

For this, you can consider WholeClear EML to PST Converter. It lets you add multiple EML files or folders, preview the emails, and convert the selected data into one PST file. This is useful when the EML files are coming from different folders or you have a large collection to move into Outlook. Attachments and email properties are also retained during the conversion.

I’d suggest checking the preview before starting the conversion, especially if you have hundreds or thousands of EML files. After creating the PST, open it in Outlook and check a few emails, attachments, and folders to make sure everything has been transferred properly.