List hygiene

Sending to unengaged or invalid addresses hurts deliverability. List hygiene is ongoing maintenance.

Regular tasks

• Remove hard bounces immediately
• Remove soft bounces after 3-5 attempts
• Suppress unengaged (90+ days no open) or win-back first
• Clean inactive subscribers quarterly

Verification

Before sending to new lists or after long gaps, verify addresses with ZeroBounce, NeverBounce, etc.

The tradeoff

Removing subscribers feels like losing. It isn't. Engaged smaller list outperforms disengaged larger.

What to do with this

• Schedule quarterly list hygiene as a standing ritual, skipping this degrades deliverability quietly until it's a crisis
• Run a re-engagement sequence before suppressing, catches some late-engagers and protects against over-removal
• Suppress unengaged subscribers even when it feels wasteful, deliverability benefit to active list outweighs lost potential
• Remove hard bounces immediately (not quarterly), continuing to send to bad addresses signals spammer behavior
• Track list quality score alongside size, a clean 30K list with 45% open rate beats a dirty 100K list with 12% open