Thank you. I'll give that a try. Having given it more thought, I won't be able to achieve this in Zapier without a multi-step Zap as I'll need a conditional filter in the middle. Will comment here if I find a solution.
The person setup as a store manager on a site I'm building only wants new order notifications for specific products (I won't bore you with the details of why).
I've spoken with Squarespace support who inform me this isn't possible.
Does anyone know of a third-party solution (like Zapier) that might achieve this? My thinking at the moment is to create a sales@ email address and send all new order emails there. Then use some Zapier trigger to forward only the required emails to the store manager. But I can't see anything in the email that I might use as a trigger for Zapier to recognise. The people I'm building for won't want another (Zapier) subscription. So multi-step Zaps would be out.