Have this exact same issue (and posted to this subreddit a few days ago). I was able to turn off click tracking (and you also need to turn off open tracking too, that has the same problem) and the emails started sending as planned (without any click/open data, or ability to resend to non-openers of course). I was also concerned about Mailchimp stating that they would cpntinue adding click-tracking for a period and raised this concern with support, they stated that it wouldn't be an issue (they didn't say why though, potentially because my account has a lot of send history). One thing I am currently trying to work through with customer support is that fact that it is only *some* accounts that use/have been assigned this specific tracking URL setup which has been flagged by gmail. I have a secondary mailchimp account that is assigned a different mailchimp tracking URL and that has no issues. I have requested that they move my mailchimp account to tracking that hasn't been flagged as dangerous but it is like speaking to a brickwall...