If I am a non-gmail user but a recipient of said mails, how can they be in a side panel? They may be a side panel for gmail users reading through webmail - but what if I read with a non-gmail mail reader?
Like I said above, are you sure the ads aren't only seen by gmail users?
Ads and links to related pages only appear alongside the message that they are targeted to, and are only shown when the Gmail user, whether sender or recipient, is viewing that particular message.[...]
Doesn't this imply that only Gmail users see the ads? Or are they actually embedded in the email so non-Gmail recipients also see them?