Free Converters have a natural appear to them that attracts everyone: they are free. It sounds great. However, if you are concerned about your data integrity and all these tiny but crucial details (like headers, graphics, attachments, contacts, etc.), then you are better off avoiding them.
OST to MBOX Free Converter
There are few professional OST to MBOX converters that come with free trial versions that you can try.
If you only have a folder or two you want to move, then free tools might work. Although, in that case, it is even better to just do it manually using a free email account and server (like Gmail). But with anything more than that, you are going to need a proper professional converter.
What You Need In An OST to MBOX Converter?
Here are certain features that you absolutely need if you want to cleanly migrate your data. Keep in mind that mediocre converters either do not offer them at all or are very limited:
- You would want to keep the folders and their structure and not just get all emails together under one mailbox or want to see the folders not reflecting the original arrangement.
- You would also want to have all the attachments, small or large, with known or un-formats, docs or executables, or anything like that correctly converted from OST to MBOX. Many generic solutions fail to retain certain types of files as attachments.
- If your OST file is too large, you would want to split the large MBOX file into smaller files.
- For more advanced users, a detailed conversion log at the end can be priceless. Without a proper report of the process, a large migration project that needs to be done through multiple times can become unnecessary daunting.
Most free OST to MBOX converters fail to deliver on those above stated features. Some might claim to offer them, but they do not work many times, especially with large files rich in content.
On top of that, there are aspects like interface, speed, tech support, and more that are sadly never given with free converters, making professional users disappointed. Even if you do not have business related contents in your files, you can still face dire consequences like data loss and ineffective outcome without the essential features.
It is at this time you have to choose either you want to still try your luck and hope a free tool works or choose the right way the first time. A professional tool might not free, but in the long run, it is non-professional and poor software solutions that cost you more, in terms of time, efforts, and resources.
The Best OST to MBOX Converter
If you are short on time and do not want to scourge the web for internet, we can recommend you an excellent OST to MBOX converter that is available to download for free as a trial, called ‘OST Extractor Pro,’ from USL Software. It comes in both Windows and Mac edition.
It convert ost files to pst, mbox, eml, Apple Mail, Thunderbird, Postbpx etc.

Get the OST to MBOX Converter free trial
After you used it personally and seen it in action, there are several licenses that you can pick one from based on your needs.

Note that OST is not the personal data file like PST is, and therefore, trickier to process it into another file like MBOX. If you were looking to convert PST, there is another equally proficient converter for it: PST Extractor Pro (only for Mac).