The email senders tab will show you all your email senders
To see the email senders go to 'PEOPLE' > COMMUNICATIONS' > 'EMAIL SENDERS'
The email senders tab will show you all your email senders, their Username, signature and status, as shown in the image below:
You can recheck the DNS (Domain Name System) of the senders by clicking on the 'EDIT' tab in the top right corner.
Click on a senders 'Username'. A new window will open to the right.
Then click on the blue 'RECHECK DNS' button.
The status will then show under the 'STATUS' tab.