Spam filters are designed to protect users from unwanted emails but can sometimes mistakenly classify legitimate emails as spam. To avoid this, focus on creating relevant and engaging content, and avoid excessive use of images and links. Use clear and concise subject lines, and personalize your emails to make them more relevant to the recipient. Additionally, ask your subscribers to add your email address to their contact list or whitelist your domain. Regularly test your emails using spam filter testing tools to identify and rectify potential issues before sending out campaigns.