Using the Email Sender feature you will be able to see and control all the email addresses used to send emails to attendees or invitees.
Checking 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. You may also look up for a sender using a term or filter a specific category (all, sent, not configurated, etc).
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.