After searching the net for months, I have come across a solution that can hopefully benefit some of you. Please refer to this site to setup an IIS SMTP relay if you have access to a server with IIS: How to Configure IIS for relay with Office 365. Make sure you add the ip addresses of the computers that are sending the emails to the allow lists.

The one step it doesn't provide is how to configure multiple email addresses. We had a spare user license available so we created a new user called "documents". This is the email address we used in the steps provided above. Once that was created we gave that account permission to send as other users. This is accomplished by adding the "documents" account to each of the accounts that you use in Sage 500. From the admin center of Office 365 online, click on the user you want to use. Proceed to mail settings and click edit for Mailbox permissions. Under "Send as" add the "documents" account. Hit save and your good to go.

Hope this helps some of you.