Those emails are obfuscated to prevent spam spiders from collecting them; the technique isn't perfect, i.e. a spider could be written to harvest these emails anyway, but I don't think it's likely. Image-based email addresses are probably the most secure from spiders, but the Smarty library which provides mailto obfuscation doesn't support them, and they're irritating to users because they must be typed in rather than simply clicked.
We might support image-based email addresses in the future, but for the moment it's not a priority as they've already been obfuscated in a way that's sufficient for the near future.
Public Knowledge Project Team
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