If the e-mail address is posted as text then it can easily be retrieved by various methods most notably being "web robots" that scan web pages for the @ sign and the web page. Having this they believe they have an e-mail address.
Using an image with the address in it then the action is simply a mailto: function. The contents of the image can not be read.
Also, the "contact us" feature in the LL webshop works extremely well.
I know it doesn't have quite the same convenience as a mailto link or a posted, non-obfuscated email address, but it certainly does the job.
I've had my email address posted on the web for over a decade (but not for the past year or two), and I receive so much spam that I simply cannot use my regular email address (@ifi.uio.no: jani, BTW), but instead have to supply per-contact email addresses (e.g. jani+usethis@ ...) so that people can easily reach me. I really don't want anybody else to have to resort to similar measures, it's pretty inconvenient.