Hello, JulieMES.

We don't want to give up just yet. I appreciate your time in doing the suggested fixes. I also tend to fix program issues myself. Though, there are times that I have to resort to calling support when all else fails. Before we do that, I have a bunch of steps we can use to resolve the email issues. 

You might have already tried these steps, but let's give them a shot. Let's start with the basic step. Let's make sure to update QuickBooks to the latest release. 

The issue might also stem from Outlook itself. We can repair it to see if this has something to do with damaged software components. You can click here for the steps: Repair an Office application.

We can also try deleting and recreating those invoice or estimate templates. There are instances that a damaged template prevents you from emailing those transactions using Outlook. 

Here's how to delete a template: 

1. Go to the List menu, then choose Templates. 
2. Find and open the estimate or invoice template. 
3. Click the Manage Templates button.
4. Highlight the template, then click the Copy button.
5. Delete it after creating a copy by clicking the Delete button.
6. Once done, click OK. 

Use the copied template to your sales forms, then email them. 

We can also use the Email later feature. Here's how: 

1. On an invoice or estimate window, tick the Email later box at the top (see screenshot on where to find it). 
2. Go to File, then choose Send forms.
3. Select the invoices or estimates, then click Send now. 

If you still can't email an estimate or invoice, I'd recommend contacting our support. They can look at the program and check what's preventing you from emailing the forms. Here's how: 

1. Go to the Help menu, then choose QuickBooks Desktop Help (alternatively, you can press F1).
2. In the Have a Question window, click the Contact us link at the bottom.
3. Choose Solving Issues & Error Messages then Common Errors for the topics.
4. Scroll down, then choose how you want to reach us. 

After sending the invoice or estimate successfully, you can run sales-related reports to help you check how much you've earned. You can click here to open a guide: Reports and Accounting.

You can always visit here if you have concerns regarding the sales forms in QuickBooks Desktop. I'm also open to answer any other future questions you might have.