That the possibility for an email client to be so configured that it would AUTOMATICALLY process a false positive validation, makes this system utterly unusable for any developer with a [brain|conscience].
If the purpose of the validation is simply validation, then what you call a false positive isn't actually false, as the e-mail address evidently was valid.
Including a very clear "I did not ask for this" link in the e-mail would allow false positives to undo any damage done.
Just because a technology can be used for bad (and this one is indeed - anyone auto-loading images in e-mail will be flooded with spam for that exact reason) it does not imply that any use of the technology is bad.
That the possibility for an email client to be so configured that it would AUTOMATICALLY process a false positive validation, makes this system utterly unusable for any developer with a [brain|conscience].