There are a few approaches you could take. One method without having to use XSLT would be to use IF expressions and base if off of the Source Mailbox Name.
In the email listener configuration, check the 'Include Source Mailbox Name'
Now under the Incident object, business rules, you would need to add an IF expression for the fields: Category, Subcategory, and Team.
Example would be:
The same could be done for Subcategory and Team as well. You can have multiple nested IF statements as needed to meet your requirements.
Keep in mind, that Category is usually driven off of Service so will need to ensure you are setting valid values within the business rule.