How to Improve Your Sender Score for Better Email Deliverability

Your sender score is the email equivalent of a credit score—a numerical ranking between 0 and 100 that inbox providers use to evaluate the trustworthiness of your sending IP address and domain. Calculated by companies like Return Path and Validity, this score aggregates data from ISPs, mailbox providers, and email filtering services to predict whether your emails should be delivered, quarantined, or rejected. A score above 90 is considered excellent; anything below 80 signals deliverability risk that requires immediate action.

The most significant factor in your sender score is your spam complaint rate. Inbox providers measure how many recipients mark your emails as spam, and the target threshold is below 0.1% per 1,000 sends. Exceeding this threshold will drop your sender score rapidly. To minimize complaints, use confirmed opt-in for all new subscribers, make unsubscribe links visible and functional in every email, and ensure your email content matches the expectations set during signup.

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Bounce rates are the second major component of your sender score. Hard bounces—emails sent to invalid or non-existent addresses—should be removed from your list immediately. A hard bounce rate above 2% indicates poor list hygiene and will drag down your score. Use email validation services to clean your list before major campaigns and implement real-time bounce processing through your ESP to maintain list health automatically.

Engagement metrics also influence your sender score indirectly. Inbox providers track how recipients interact with your mail, and low engagement signals that your content is unwanted. Implement a sunset policy that flags inactive subscribers after 60 days and moves them through a re-engagement workflow. Suppress subscribers who remain unengaged after 90 days to keep your engagement metrics healthy and your sender score strong.

Monitor your sender score weekly through tools like Validity's Sender Score Resource, Google Postmaster Tools, and Microsoft SNDS. Investigate any sudden drops immediately. If your score falls below 80, pause non-essential sends, audit your list hygiene, review recent complaint data, and identify the root cause before resuming normal volume. Rebuilding a damaged sender score takes three to six months, so prevention is far more effective than remediation.