Declined meeting requests "Auto Deleting" from Inbox

One of our user is having this issue. When she sends out a meeting request and it is declined by receiver she gets a "declined" message in her inbox as normal. But in few minutes it get auto deleted and goes to her deleted items.

I tried looking up Outlook options but cannot find anything for it. Anything slightly like this is Outlook option "Delete meeting request from Inbox while after accepting" does not apply to us

Can someone please help.