Errr,
We show e-mails as an in line graphic, if you look behind the scenes by pulling up the raw coded page you can see email addresses are also encrypted. So, we stop the spybots and automated harvesters.
However, each complainer has chosen, has actually opted to make their e-mail address available to other users. You can check for youself by holding the mouse down over the username - try both matelot and Land After as examples.
If people chose to accept e-mail from others and there are low wage economies where they will go through the angst of stripping the contact details there's not a lot else we can do.
The reality however is that is not terribly cost effective and ISP's have a serious problem with staff, errr boosting their incomes.
Stables and bolted doors and all that: You can change your userCp up near the top of every page to block your email from being available to others. Personally I'd destroy the problem email address from your system, get a new address, go into userCP and change them over. At the same time check that you don't have the option for others to e-mail you selected.
Regards
Rob