User set up an email message to appear on invoices; however, it is not showing up.
This can happen if you have set up the message in the Settings > Company > Email Settings screen while the option Allow User Settings to override these email settings at the top is checked. This option configures CORE to use the email settings specified at the user-level in User Settings instead. If you did not set up the message there, you cannot see it on the invoice emails as that option is getting precedence.
To fix this, you can uncheck this option in Settings so that CORE uses the message specified here globally for all users. Otherwise, you can keep it checked and set up your message from the User Settings > Email Settings.