When the import export option is greyed out in Outlook , it's usually due to account restrictions or Outlook configuration. This is common with Microsoft Exchange or Microsoft 365 accounts managed by an organization, where administrators disable importing and exporting to protect company data.

Other possible reasons include:

Corrupted Outlook profile.
Outlook running in Safe Mode.
Group Policy restrictions.
An outdated Outlook installation.

If your goal is simply to export emails from a PST file, you don't necessarily have to fix the Import/Export option first. Tools like Advik PST File Converter can read PST files directly and export emails to multiple file formats without using Outlook's built-in Import/Export feature.