In 2025, tools like eSoftTools MBOX Splitter and Merger offer advanced features for this, allowing you to split by size, date, or year, and merge multiple files. Some email clients have basic features, but dedicated software provides more control. While manual methods exist, they're risky and time-consuming. Choosing the right approach depends on your needs, but proactive management of your MBOX files, whether through dedicated software or email client features, ensures a smoother email experience.