This is a cop-out article that MailChimp can direct its customers to when they ask "how to disable spam filters." I worked in support for another ESP, and customers would often have unreasonable expectations about email delivery rates. Enough industries are corrupted, that customers thought that with enough money, we could bypass spam filters, or ensure 100% deliverability (never mind that half their email addresses…
If you only send mail to people who have willingly opted in, not through trickery, pressure, inducement or some BS promotion, they'll actually want to read your mail and won't tolerate it being binned with the SPAM.
Unfortunately, a lot of business people don't get that.