Email address field to contain organisation's domain

Is there a way to set up the email field so that it must contain a certain string? For example, we want to ensure the user uses their company email. If the email field doesn't contain @bloomhearing.com.au, an error message will appear.

I tried using the a calculation condition and a show/hide for the error message. However, as they start to enter their email address, the error message will show, causing confusion and frustration.

Is there a way for the validation to work AFTER the user has completed the filling in the field?

Unfortunately, that is not possible. However, please note that you can disallow free email addresses.