Importing OLM to Gmail becomes easier when using the right tool, especially for users handling large data sets. I recently tried OLM Converter and found it quite effective. It supports formats like PST, MBOX, PDF, EMLX, MSG, and HTML. It also allows migration to email clients, including Gmail, Yahoo Mail, Thunderbird, Outlook, and Office 365. The tool ensures data security and preserves the folder hierarchy. It also includes features like selective conversion, duplicate removal, and attachment management. I was able to process large files without any issues. Overall, it seems like a complete solution.