Hi Sudhanshu,
I noticed you are using Outlook for Mac 14. Would you mind updating to Outlook for Mac 15 to test the issue? Please refer to this article to download the latest version: http://blogs.office.com/2014/10/31/new-outlook-mac-available-office-365-customers/
Does this issue happen on other users? Could you provide us with a screenshot regarding this scenario?
Thanks,
Dunk
