In Microsoft Outlook, when you double-click to open a Microsoft SharePoint alert notification that is forwarded to you, voting buttons that the sender added may not be visible. This behavior occurs despite the following message that is shown at the top of the message:
Vote by clicking in the Respond group above.
The Share Ribbon tab on the message that is opened contains custom SharePoint buttons, such as the Connect to this Document Library button and the Preview this Document Library button. The original Message tab, where the Vote drop-down button typically appears, is not available. .
Use the Reading Pane to access the voting options. To enable the Reading Pane, follow these steps:
In the main Outlook window, click the View Ribbon tab.
Click the Reading Pane button, and then click either Right or Bottom.
Click one time on the message that was forwarded to display the message in the Reading Pane. In the message header area of the Reading Pane, click Click here to vote to make a voting selection (The sceen shot for this step is listed below):