Insert a link to an Outlook email within Excel

I am trying to create a hyperlink in an Excel cell to an existing Outlook email.

The user should be able to click on the link in the cell (could be a button with VBA code as well) to open the email.

I know that pst files have to be opened within Outlook(?), so let's assume Outlook is running with the relevant pst file already open.

I found nothing to provide a clickable way to open email.