How can I recover crucial email attachments after a key employee leaves suddenly?

A few months ago, one of our senior project managers resigned without prior notice. She had been handling several major clients, and unfortunately, a lot of the communication and contracts were stored exclusively in her email account. By the time we realized what had happened, the IT department had already deactivated her account. Panic set in when we discovered that some of the original contracts, project briefs, and signed agreements existed nowhere else. It felt like the entire operation for those clients was hanging by a thread.