You may import multiple import MBOX files to Spark Mail by using MacProTools MBOX Converter for Mac. The program has easy-to-follow, non-technical stages and is both secure and user-friendly. It also offers many tools that enable users to import MBOX files to Spark Mail per their requirements. Mac users can use the well-reviewed MBOX Converter to attempt converting MBOX files to Thunderbird for free. You can import the first few MBOX emails and attachments into Spark Mail for free.