The most obvious way for Google to mollify Gmail critics would be to allow users a chance to opt out of the targeted ads, and hope that most won't bother. Brin insists the company has no plans to do that, contrary to recent news reports, but he says it hasn't been ruled out, either. In return for turning off the company's ad targeting system, Google could offer, say, only 10 megabytes of disk space to those who opt out. It would still be a better deal than Hotmail and Yahoo! Mail, and skittish customers might reconsider the ads as they near their inbox quotas. Still, critics would demand that the ad-targeting system be opt-in instead of opt-out, even though they make no similar demand for spam-filtering software. What's more, the opt-out solution wouldn't assuage non-Gmail users who fear their missives to opted-in Gmailers will be handed over to advertisers, or worse, John Ashcroft.
Luckily, there's a better option. Ten years ago, the privacy objections of people who didn't want their Web sites crawled by search engines were put to rest with a simple fix: Webmasters could place a file named robots.txt on their sites as a "No Trespassing" marker, a sign that they didn't want their site to be searched. Google needs to offer a robots.txt for e-mail, some kind of tag that any Web user can include in a message to indicate that it shouldn't be scanned by Gmail software. Given that antispam and antivirus software will scan the e-mail anyway, this solution would be somewhat phony. But if McCullagh is right that Gmail-bashers are just opposed to helping advertisers, it will do the trick.
The Google guys need to implement this before the backlash gets out of hand. Otherwise, they may be forced to abandon the best Web mail system yet because of a few well-placed people who've never even tried it. That really would be evil.