First I tried to use my legitimate email address I use all the time to sign up and I kept getting a message to "Please don't use a disposable email.", even though it is NOT a disposable email at all so not a good sign already for an email address finder app.

So I simply tried installing the hunter add-on to the Firefox browser using the AMO site and doing this I got the message "The add-on downloaded from this site could not be installed because it appears to be corrupt" each time I attempted to install the add-on.

So I created another email account to try and sign up via the hunter website and then tried to search for our dentist to see if we could get his email address (which is why I was interested in hunter in the first place) and did not get any information that helped at all.

Just for kicks, I did a "verify" on my email address that hunter considered a disposable address and what do I get?

Besides "risky email address" which is no help I got the following two red "X" results:

It looks like a gibberish email address.
It is a disposable email address.

Well it's not a "gibberish email address" as I use it daily and have been for years.
And obviously it is not a "disposable email address".

Not very reliable if you ask me, clearly the parameters Hunter uses are failing to provide accurate results proven out by testing my own email address that hunter assumed was "disposable" and presumably an invalid address based on the reference to "gibberish" regarding my valid email address.

And lastly, I got more useful information from https://verify-email.org/# which is available to anyone on the web without signing up.

I rarely post reviews for software but in this case considering the degree of failure I felt compelled to post a review considering the difficulty just signing up for the app or the inability to install the Hunter Firefox add-on not to mention the bogus results for my personal email which is totally valid and not at all "disposable", WOW!!!