Users of Outlook 2016 for Windows have reported delayed or undelivered email messages when they are generated from Polaris (Comment Cards), The Financial Reporting Tool or other applications such as Excel. If Outlook 2016 is not open when an email is generated from another application, the email is stored in your Outbox and is only sent after the Microsoft Outlook 2016 application is re-launched.
Resolution
Launch the Outlook 2016 prior to sending an email from an application such as Polaris, The Financial Reporting Tool or Excel. This will allow to email to be delivered as soon as it is sent.
If the email you sent was not delivered, launch Outlook 2016 and click Send/Receive > Send/Receive All Folders to deliver all messages in the Outbox.