Deliverability
List hygiene and spam traps: why removing contacts increases revenue
19 November 2025 · 8 min read
Sending to an address that will never open costs a credit and a small amount of reputation. Sending to a spam trap costs the domain. Neither shows up in revenue reporting, which is why unhealthy lists persist for years.
List hygiene is the least glamorous and highest-leverage work in email marketing. Here is what to remove, how to find it, and how often.
The two kinds of spam trap
A pristine trap is an address that was never used by a person and was published only to catch scraped or purchased lists. Hitting one indicates the list was not collected with consent, and the penalty is severe.
A recycled trap is an abandoned real mailbox that a provider has repurposed. Hitting one indicates you kept mailing an address long after it stopped responding — a hygiene failure rather than a consent failure, but damaging all the same.
Thresholds to act on
| Signal | Acceptable | Act when |
|---|---|---|
| Hard bounce rate per send | Under 0.5% | Above 2% |
| Soft bounces, same address | 1–2 occurrences | 3 consecutive sends |
| Complaint rate | Under 0.10% | At or above 0.10% |
| No opens or clicks | Under 90 days | 180 days or more |
A quarterly cleaning routine
- Remove every hard bounce immediately and permanently — this should be automatic, not a quarterly task.
- Suppress addresses with three consecutive soft bounces.
- Segment contacts with no opens or clicks in 180 days into a re-engagement group.
- Send that group one short re-permission message; suppress everyone who does not respond.
- Delete role addresses that were never opted in individually: info@, sales@, admin@, postmaster@.
- Never buy, rent or append a list. Purchased data is the fastest route to a pristine trap.
Why a smaller list usually earns more
Engagement is the dominant input to inbox placement. Removing contacts who never open raises the aggregate engagement rate of every subsequent send, which improves placement for the contacts who do open. The list gets smaller and the number of messages reaching an inbox goes up.
It also reduces cost directly: credits spent on addresses that cannot convert are pure waste.
Key takeaways
- Pristine traps signal a consent problem; recycled traps signal a hygiene problem.
- Hard bounces must be suppressed automatically and permanently.
- Re-permission dormant contacts once, then suppress them.
- Cleaning improves placement for the contacts who remain.
Sources
Put this into practice with HTsend
Everything in this guide is built into the platform: authenticate a sending domain, clean your list before you send, and watch inbox placement in real time.
