If you want to fix errors in oversized OST files, I advise you to get SysInspire OST to PST converter software. This tool converts OST files into multiple file formats such as OST to PST, EML, EMLX, Office 365, Yahoo Mail, Gmail, etc. It has technical support and all users get help by email or live chat. This tool has a demo version that can convert 25 items from each folder of OST for free.

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