How to Clean Your Email List

List hygiene is one of the most reliable ways to improve email deliverability. A smaller, cleaner list that engages well outperforms a large list full of inactive contacts every time — in open rates, click rates, and inbox placement. The deliverability logic is simple: inbox providers watch engagement. When too many recipients ignore your emails, they start routing your emails away from the inbox for everyone.

Why Cleaning Matters

• Hard bounces (invalid addresses) damage sender reputation when they accumulate
• Inactive contacts that never open drag down engagement metrics
• Spam trap addresses hide in old lists and trigger blacklisting
• A smaller, engaged list is literally more valuable than a larger, disengaged one

Who to Remove

• Hard bounces: MONDAi automatically suppresses these — confirm they are suppressed and not still receiving campaigns
• Soft bounces (repeated): Three or more soft bounces in a row = effectively invalid
• Unsubscribed contacts: MONDAi automatically marks these — confirm they are not being sent to
• Chronically inactive: No email open in 6+ months with 10+ emails sent

Steps

Common Mistakes

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Next Steps

• Deleting contacts instead of suppressing — suppression preserves the history and prevents the address from being re-imported later.
• Never running a re-engagement campaign before suppressing — you will remove people who would have responded.
• Cleaning once and considering it permanent — list hygiene is an ongoing practice, not a one-time event.
• Waiting too long to clean — clean quarterly.