Here is a way to uncover all that that extension does - even without the need for Chrome or Gmail. This link works in any browser - Chrome, Firefox, Opera, or any other.
Replace the email address at the end with an email that you would like to use - and find the person's LinkedIn profile. (This link can also verify that the email address exists.) The link works reliably, and it's fast! You do not need a Sales Navigator subscription; you need to be logged into LinkedIn.
Here is what you would see when using the link above: