I hope that this question is reliable as I guess all webmasters send out emails of one sort of another.
I read a while back that gmail has started downloading all pictures attached to emails. As far as I understand, this totally ruins any email tracking technology, which tries to measure how many percent of users that looked at their emails, since the way they measured this was to see how many percent of people that downloaded the attached images. Is it correct that it is impossible to track whether a gmail user has looked at an email? Is it also true for the other large providers like Microsoft and Yahoo? If so, then there really is no point in buying tracking services for email campaigns at all, am I right? I do understand that one can still reliably track which links were clicked.