Providing info email or contact email in plain text helps spammer (robots) to extract the email using regex or any technique, currently I provided an image like this:
But this method has usability issue because users with enabled default email can't click it and start sending email using default mail sender, also, user can't even copy address and paste it.
Having tried a bunch of different methods in the past, my answer, at least as far as "unspammable" goes, would be "You can't."
Even with your image technique, or no matter what else you do, as soon as somebody does e-mail you they'll have your address in their address book. And then they'll get infected by a virus that steals their address book and sends it to a spammer.
Frankly, if it's your own address, I wouldn't even bother. Just set up a separate e-mail account for your web-related e-mails and use a good adaptive spam filter on it. Remember to occasionally skim your spam folder for false positives.
If you're dealing with addresses belonging to other people (e.g. your users), it does seem prudent to exercise a little extra care. In fact, the first question I'd ask myself is whether you even need to reveal your users' e-mail addresses in the first place. You can always implement an "e-mail another user" feature on your site without actually revealing the recipient address to the sender. At the very least, I'd say that making their e-mail address public should always be optional (and opt-in, not opt-out) for the user.
I would also suggest that you probably shouldn't show a user's e-mail address to anyone who isn't also a registered user of your site. This may not stop all address harvesters, but it should stop the majority of them. Preferably, you should also use a good CAPTCHA as part of your account registration process, and you may also want to wait until a new user has participated enough on your site to confirm that they're not a bot before granting them access to abusable features such as other users' addresses.
Have you thought about JavaScript obfuscation? There are a few different ways of achieving that, one service which would provide the output for you is hivelogic.
Rather than have a email address on your site, I would suggest using a form that users can use to contact you. A contact form is much better at spam control than email:
In addition contact forms allow you to prompt the user for specific fields and validate that their responses match a valid pattern. While contact forms can be configured to be free-form, email is always free-form.
I am the author of a free, open source contact form that you can use on your website.
