Error message "Please specify an email address" when saving a sales order with a drop-ship item

The error message is referring to other email addresses aside from the customer's.  Since the option is selected to automatically email drop-ship POs, check the vendor record if it has an assigned email address.

To check this:

1. View the item record and go to Purchasing/Inventory tab > Vendors subtab.
2. Click the vendor link.
3. Edit the vendor record and add an email address.
4. Click on Save.