We can’t email within ERPNext. QuickBooks email button opens Outlook email. Can ERPNext do the same?
Not out of the box in the same way QuickBooks does it. ERPNext’s standard Email action stays inside ERPNext and sends through the configured Email Account.
If you specifically want Outlook to open, the usual workaround is a small custom button or client script that builds a mailto: link from the supplier contact on the PO. That will open the machine’s default mail app, but ERPNext will not track the send status from Outlook.
I’d check the built-in Email Account route first, because that’s the supported path. If that is not acceptable, then a custom mailto: button is usually the clean fallback.