Thanks for coming here, Jeremy0333.

There is an ongoing investigation about the error when sending invoice specific to QuickBooks for Mac 2020. Our team of engineers are closely working on getting this resolved.

For now, they have released a couple of workarounds for your to try. The first option is to make sure the QuickBooks for Mac 2020 is listed and authorize. To do this, please follow the steps below:

1. Go to System Preferences and choose Security & Privacy.
2. Click Automation. 
3. Open the Mail App, then open QuickBooks Mac 2020.
4. Locate the invoice that you want to send and click the Envelope icon to send the email.

Another way is to simply open the invoice and send it as a pdf attachment. Below are the steps on how to do it:

1. Locate the invoice you want to send.
2. Click on the Print icon.
3. Choose PDF Save as pdf.
4. Then, send pdf as an attachment.

While we continue to investigate the cause of this error, I suggest contacting our QuickBook Care Support. This will help us know the number of users affected and to make sure you'll be updated once the fix is available. Our team will communicate with you via email.

Here are the steps to contact support:

1. Click Help at the top menu and select QuickBooks Desktop Help.
2. In the Have a Question? window, enter a topic.
3. Click Contact us.
4. Hit the Get a callback button.
   

Get back to me if you have additional questions. I'll be around to answer them all for you. Keep safe and have a nice day ahead!