When leaving an email address on a blog, forum, website and/or any other public place, there will be a risk to receive spam from non-human beings, but robots.
So, how to leave an email address safely and to protect your inbox from spam?
You can display it like “abc AT gmail.com” instead of “abc@gmail.com”, turn it into an image, or replace it with a URL, as mentioned before.
The following will show you another way — to hide it by an HTML code with reCAPTCHA Mailhide, which is developed by Google and available for you to protect your email from spam by turning its address to an HTML code.
On the reCAPTCHA Mailhide site, you just need to enter any email address and click on the “Protect It!” button:
After that, your email address will be turned to an HTML code automatically:
Copy and paste the HTML code on any page, you can see your email address is hidden like the following:
esse…@gmail.com
When clicking on “…” the user must solve a reCAPTCHA before they can see your email address.
Besides HTML code, reCAPTCHA Mailhide will also turn your email address into a URL, which will look like the following:
http://www.google.com/recaptcha/mailhide/d?k=014WF9bb-M8xROyPn4fymFzA==&c=lobQZgOL2kLzUAt_Dxn7zc_3SjcK-ddmkRzNtV91Zz4=
The above URL will link to the same reCAPTCHA page as the HTML code does, as what you can see from the following screenshot:
When solving the reCAPTCHA, you can see the full email address:
That’s how reCAPTCHA Mailhide basically works.
Besides, you can also customize the HTML code by changing the hidden characters, title, window size, etc., and you can even use the reCAPTCHA Mailhide API to protect other people’s emails from spam, too.
Although reCAPTCHA Mailhide is good for you to protect your email from spam, it is difficult to enter a reCAPTCHA, why Google doesn’t let people to select instead to enter just like what Scr.im does?
What is more, the generated URL was too long and too ugly, why Google doesn’t make it shorter and beautiful with its goo.gl shortening service?
Maybe Google just doesn’t care reCAPTCHA Mailhide so much. 
Update: reCAPTCHA Mailhide is not workable any more.
