Data decay is the steady loss of accuracy in contact data. People change jobs, companies rename or close, and email addresses are switched off. A list that was accurate when you built it starts going wrong straight away.
How fast
B2B contact data is commonly estimated to decay by around 2% a month, roughly a quarter of a list each year. Lists in fast-moving industries decay faster.
What it costs
- Bounces: dead addresses bounce and damage your sending domain.
- Spam traps: some abandoned addresses become recycled spam traps.
- Wrong people: emails reach someone's successor, who never had the problem you're writing about.
Keeping ahead of it
- Verify every list right before a campaign, not just when it was bought.
- Don't save lists for months; build them close to when you'll use them.
- Remove bounced addresses at once, and treat "they've left" replies as updates.
Re-check a list with the free email validator.