Rules of thumbs:

  1. There isn't any method that is 100% efficient and safe. It is just a matter of time before some crawlers implement a countermeasure to it.
  2. Methods that you can find by googling or mentioned on StackOverflow are likely no longer safe. (But still better than plain text.)
  3. Showing email address in an image is definitely not the way to go. Don't you see captcha has surrendered to text recognizer and moving away from text in image too?
  4. You are relatively safer if you implement your own algorithm because crawlers are less likely to spend their time implementing a hack just to harvest email addresses on a single site.

Ideas:

  1. Email address is loaded & rendered only after some user action, e.g. clicks or scrolls.
  2. Email address is only shown to authenticated users.
  3. If the email is meant for customer support, use a contact us form instead. (Add a captcha too if needed)