I am using Windows 7 Home Premium with Outlook Office 10 Apparently the zoom slider is greyed out if you are not using the reading pane. When your incoming email is zoomed, the easiest fix is to hold Ctrl as you roll the mouse wheel (this is the likely cause for many people). Keyboarders can use.
 
 

Zoom slider is greyed out in outlook 2016 – none:

 
When your incoming email is zoomed, the easiest fix is to hold Ctrl as you roll the mouse wheel (this is the likely cause for many people). Keyboarders can use. First, in Outlook and Outlook you can click and drag the zoom slider in the bottom right of the message window to the right to increase zoom level. (3) If the zoom slider does not appear in the status bar in Microsoft Outlook and higer version, you can right click on any blank place.

Zoom slider is greyed out in outlook 2016 – none:

 
 
Solution: You can go into View – view settings – other settings and change the column font and row font, standard i think is 8pt. 1.) Disable the automatic column sizing option in one of your Outlook mail folders, so the view is how you want it. 2.) Select View > Change. I’m running Office and can’t seem to change the zoom on Outlook. a zoom option on the View tab, and the zoom slider is grayed out.