Hi belmarnorthhoa,
Let's select the sales transaction you need and get this batch email option work for you.
To clarify, are you trying to send a batch email of your sales transactions on the Sales page? If so, let's make sure that we're only selecting invoices and sales receipts from the list. The Send transactions option get grayed out if you include customer payments in that batch email you're attempting to send.
Feel free to see the screenshots below to see what I exactly mean.
If you haven't already, you can read this article for more details: How to Email or Print Multiple Invoices and Sales Forms at One Time.
Let us know if you're having a different experience than what's discussed above, or if you have any other questions. We're always glad to assist you.