We've been running Postmark for over ten years, protecting our customers and IP reputations from spammers. Our spam threshold is low due to our belief that true emailing should generate no spam complaints. Transactional emails, such as sign-up confirmations or comments notifications, are expected by the user and should not generate complaints. To fix this, review your app and transactional email templates to ensure clear branding, relevant "From" names, addresses, and subject lines. Marketing emails can also generate more spam complaints if recipients' expectations aren't met. To minimize these issues, get explicit permission from recipients, work on message content by personalizing and making subject lines engaging, make the unsubscribe experience smooth, and address user errors that may lead to spam complaints. Ultimately, expectation is key in maintaining a healthy sending reputation.