You implemented all the authentication to whitelist your domain, yet campaigns still end up in spam folders. This can happen for several reasons, including the sending email address, subject line, or message content.
Even legitimate and innocent campaigns get trapped in spam filters based on small issues, like your sending name or email address, or information shared from other spam filters. We can't tell you if your campaign ended up in junk folders. However, your reports page contains helpful information that can help you improve your campaign deliverability.
If a lot of your recipients click the Report Spam button in their email client (e.g., Gmail, Yahoo), those services will start blocking your campaigns and deliver them straight to the spam folder.
If a recipient tells you he or she clicked Report Spam by accident, many email services include a Not Spam option. Ask the recipient to find the email in the spam folder, and mark it as Not Spam or Not Junk. Buttons and labels will vary by inbox. This helps keep future messages out of other recipients' spam folders, too.