In Windows 10 Pro, I am getting a dialog box of MS Office outlook repeatedly, why?

[Windows Central Question]

In Windows10 Pro, I am getting a dialog box of MS Office outlook repeatedly, why? fedup of this

I am Using Windows10 mail app, but repeatedly a dialog box appears after some time having the message "Either there is no default mail client or the current mail client does not fulfill messaging request. Please run MS Outlook and set it as the default mail client". How to get rid of this?