Let me chime in and share some tips on how to send an email to multiple customers, Q-AskAlot. 

If you're using QuickBooks Online (QBO), you can add multiple emails within your forms or your customer's window by adding a comma "," after typing the first email address. Let me explain the process in detail: 

To add multiple email addresses within your customer's profile: 

1.  Go to the Customers & Leads menu and choose Customers. 
2. Find your customer by typing their name in the Search bar or by scrolling down, and then clicking on their name.
3. Click on the Edit option located beside the New Transaction option.
4. Within the Email field, type the first email of your customer.
5. After adding the first email, add a comma, and then type the name of their second email address. 
6.  Once done, press Save. 

To add multiple email addresses within your forms: 

1. Go to the left navigation panel and click on the +New icon. 
2. Choose the transaction you want to create. 
3. In the Email field, type the first email of your customer.
4. After adding the first email, add a comma, then enter their second email address. 
5. Fill out other information as required. 
6. Once you're done, press Save. 

You can also customize invoices, estimates, and sales receipts in QuickBooks Online to add some personalization and specific information to your sales forms. 

If you have any other questions, feel free to leave a comment below. I'm always here to provide some assistance.