They're lucky Google even deliver them to any tab - based on their own figures it's almost a 90% chance of their email being binned by end users (OK, not opened but that's pretty much the same thing). On systems I administer that's way above the threshold I'd consider for blacklist/auto-reject.
Without trying to disparage their business, Mailchimp and associated 'services' are rarely providing 'quality' email in my experience and I don't get customers calling me up asking me to make sure such emails come through. Quite the opposite.
It's hard in the mass email business because most people (e.g. almost 90% it seems) think the emails are crap and don't want them or open them. If that's upsetting then don't complain. You need to look for a different business where you'll feel more loved and appreciated. Mass email is not it and never will be.