Corrupt MBOX files can quickly turn a simple migration into a frustrating mess--missing emails, broken headers, or import errors that stop the process entirely. If you're working with Thunderbird, Apple Mail, or another MBOX-based client, the first step is to protect your data: make a copy of the MBOX file and verify you have enough disk space before attempting any repair. To start fixing corrupt MBOX files, remove duplicate folders, compact mailboxes (if supported), and isolate the problem by splitting large MBOX files into smaller parts. Many corruption issues happen due to oversized files, abrupt shutdowns, or bad add-ons, so checking the file's integrity and rebuilding the mail index can also help. Once repaired, exporting to Outlook becomes easier. Outlook doesn't natively import MBOX, so you'll typically convert MBOX to PST and then import the PST into Outlook using the Import/Export wizard. For important or heavily damaged mailboxes, an MBOX to PST converter can preserve folder structure, attachments, and metadata while ensuring a successful export to Outlook without data loss.