If you sent a test email to a personal account and the email went to the spam folder, then you may have acquired a bad sending reputation.
A bad sending reputation means that Mailbox Providers don’t trust you as a sender and is often the result of a high spam complaint rate, low engagement rate (opens, clicks, replies), and other various factors.
Check out the “Email Sending Reputation: How Does Domain Reputation Work?” blog post to learn more detailed information on domain reputation and how to avoid high spam complaint rates.