UNITED STATES—Given the abundance of mail systems, it is hardly surprising that users often switch between them. Outlook has a few crucial advantages over Mozilla Thunderbird. For example, it is more secure and better suited to business needs. However, it is not easy to move your correspondence, as the environments are based on different file formats.

Thunderbird stores all of your email as MBOX, while its strongest rival recognizes PST. Conversion is far from straightforward without a specific utility. Dedicated software is the only way to import Thunderbird to Outlook without hassle. Otherwise, exporting mail from the open-source system is complicated. Here is how you can do it if you are willing to take the risk.

Migrating to Outlook 2019

You can achieve the goal through the conversion of MBOX to EML, which is also recognized by the destination system. Exporting can be done by saving the data as EML. This format is also recognized by Outlook, so you can manage without a converter (if you have lots of time on your hands and do not mind risking your data).

Save as EML to Convert

Launch Thunderbird and select all the messages you want to convert. The combination of Ctrl+A will select all messages within a folder. Here is what to do next:

  • Find the Save as option by right-clicking on the group and choose EML.
  • Specify the folder where the exported files should be saved.
  • Select the folder.
  • Use the corresponding option to save your selection.

From EML to PST

Now, you can drag and drop your converted files into the Outlook folder. Just open their location and move them from there. Follow the steps below.

  1. Launch Outlook and head to the File
  2. You need the open/export
  3. Click on Import/Export to summon the wizard.
  4. Specify that you will be exporting to a file and proceed further.
  5. Choose PST and proceed further.
  6. Head to the location of your EML data. Subfolders must be included in your selection.
  7. Specify a new location for the converted file.
  8. Adjust the options as you see fit.
  9. Finalize by clicking Finish.
  10. Wait for the PST file to be created.

Transfer to Outlook

Finally, you can feed the files into Outlook. Repeat steps 1-3 above. This time, choose importing from another program/file in the wizard and proceed further:

  • Browse to the location chosen in step 7 above.
  • Adjust the options if necessary and proceed further.
  • Choose where to import from.
  • Select the current folder as the destination.
  • Click Finish.The Superior Way

    The manual path is feasible but lengthy. Moreover, large files are prone to corruption during the transition. In theory, you could split them into smaller bits and convert them one by one manually. Still, nothing beats automation. A converter gets the job done in a few clicks. Besides, it is the only way to guarantee precision. If the integrity of your old mail matters, think twice before tinkering with it.