I want to share an accurate solution to your concern. I've read the original post and you're experiencing a problem when sending an email, ScottGerard.

Since you are using QuickBooks Desktop for Mac 2019, your email provider can provide the appropriate SMTP settings. Ports 25, 465, and 587 are the most common for email. If you’re having trouble connecting, try different combinations of port and connection type. For example, Port 465 with Connection Type SSL/TLS or Port 465 with Connection Type StartTLS.

Then, connect your email again to your software to send the invoices (this may or may not work since you are using an outed version of QuickBooks Desktop for Mac. Here's how:

1. Go to QuickBooks, then select Preferences.
2. Select the Email icon.
3. From the For sending Emails…, section, select one of the two options ( Send using your Default Email handling application. For example, Mail or Outlook or Send directly out of QuickBooks using your Email Account. Add your email account through a separate email service, like Gmail).
4. If you chose to use your default email application, you’re ready to go.
5. If you choose a different email account, give the account a name that you can easily identify. Then, fill out the remaining fields.
6. When you press OK, QuickBooks will attempt to validate the connection to your email provider’s server. If it’s valid, QuickBooks will close the sheet and show the account in the Email Accounts list.

You’ll find the email address listed in the From field of your message. Once done, choose any account to send from. When you email a customer, QuickBooks records the message. We'll use tracking customer email as an example, but the process is the same for jobs and vendors. Here's how:

1. Go to Customers, then select Customer Center.
2. Select the customer you emailed the form to.
3. Select the Email tab. The list of the forms you emailed to that customer appears.

You can select the item in the emails list to open that transaction. If you want to stop tracking an email, you can delete it. If the same thing happens, we'll need to send the invoices outside QuickBooks. 

Additionally, I've gathered two links for the complete steps and information, depending on your scenario.

• Connect your email to QuickBooks Desktop.
• How to fix Error: QuickBooks is unable to send your email to Outlook.

Please go back to this thread and update me on how everything goes. Feel free to tap me on my shoulder if you have follow-up questions.