When unable to send invoices in QuickBooks, this issue arises if the installation is corrupted or there are incorrect email settings. A pop-up may appear on the screen saying "QuickBooks is unable to send your emails" or Error: QuickBooks is unable to send your email to Outlook." This issue can be frustrating and hold up numerous tasks. Therefore, this issue needs to be resolved to enable the maintenance of functions and the sending of invoices. ...