1. Make sure the supplier has an email on its record (Kitchen › Suppliers) – the button only appears for suppliers with an email and at least one ingredient on the list.
2. Run the Inventory Shopping List for the dates you are buying for.
3. In the supplier's card header click Send Email. An Email Preview modal opens with the message.
4. Check it and click Send Email.

The email subject is Order Request from <your business name> and the body greets the supplier's contact name, states the order date, the Requested delivery date and your delivery address, then lists Ingredient / Needed Quantity / Conversion for every ingredient whose Total Needed is greater than zero. After sending, the button changes to Resend Email. If everything is already in stock you get No ingredients needed for this supplier.