Salesforce - Generate Contact Records for Internal Employees for Use in Service Cloud

Question

I recently configured Service Cloud for my organization and for the most part it is working great. We do have an issue I can seem to solve though. The first time an internal employee submits a case (email-to-case), there is not a contact record to associate with the case, so the help desk must spend time creating a contact record for the employee before they can proceed with resolving the case. Is there a way to automate or sync with Office 365 to create a contact record for each employee?

I have considered and/tested the options below, but none do what I want:

1. I have already set up and tested Einstein Activity Capture. This is a great tool but will not sync internal (same email domain) contacts into Salesforce.

2. I know I can automate an export from Office 365 into an AWS S3 Bucket and then use AWS AppFlow to create/update contact records. This one is feasible, but I have to imaging there is a way to integrate the two platforms without exporting data into a staging area.

3. I can't use anything that requires manual intervention, like Data Loader.