My Obfuscate Mailto function is available for direct use on my site as well as a PHP and ASP function for plugging in to other sites: http://johnhaller.com/useful-stuff/obfuscate-mailto
You can view the result by plugging an email in to that form or by viewing the source on my contact page: http://johnhaller.com/contact
I had an image instead a few years back, but that's just a hassle for readers.
So I'd yes it is a problem but it's not the biggest problem.
Ultimately, obfuscating your email address might be futile
Anyone interested in starting a new experiment? I guess I will. It might get me on the front page of HN in 1 to 2 yeras!
The one that spammers haven't figured out yet is: "My name is Bob and you can email me at this domain." (anywhere in a page under bob.com).
I doubt there's any economic incentive for an email-harvester to solve the problem of even trivial obfuscation. These days you can buy tens of thousands of email addresses for a small amount of money. These are harvested from e-commerce and social media, and are much more likely to be real and current, and the targets more unsophisticated about clicking on ads.
EDIT: Actually there is an incentive; when the algorithm is applied on behalf of many naive users. So maybe the built-in algorithm in WordPress is actually more targetable than something you make up yourself. This isn't crypto; it's just obfuscation, so being original may help.
The best solution to me is to simply never have an email address visible on your site anywhere.
... and yes, before someone points it out, having a form on your site is just as much of an issue potentially.
I have my mail software set up so that I can comfortably write emails, match and track responses, and all that. If you want me to use your mailer instead, I'll probably just forget about it.
See here: https://github.com/EllisLab/CodeIgniter/blob/develop/system/...