How to Restrict Users From Entering Email IDs of Certain Domains
You can restrict users from entering email IDs of certain domains in your survey. This can be done by enabling the Blocking Emails setting:
Go to a survey's Settings >> Advanced and enable "Blocking Emails." Once enabled, enter the domains that you want to block, separated by the comma sign. For example, yahoo.com, gmail.com, and so on. When you're done, click "Save" to apply the changes.
That is all about blocking emails in ProProfs Survey.