If you run your own webserver, Nginx in my case, you can easily hide mailto links from spammers with the HTTP rewrite module.

Add the following three lines of code to your Nginx server config and replace any “mailto:user@example.com” links with “/mail/user/".

location ~ /mail/(.*)$ {
        rewrite ^/mail/(.*)/$ mailto:$1@$host redirect;
    }

The same can be done for other schemes like for making telephone calls. Again, add the code below and replace any “tel:555-1234” links with “/call/55512345/".

location ~ /call/(.*)$ {
        rewrite ^/call/(.*)/$ tel:$1 redirect;
    }

These are examples using Nginx but I bet the same can be accomplished with other webservers.