How often a stored list needs re-checking
A verified list is not a finished asset. It decays on two independent clocks, and a re-check cadence is just the decision about how far behind those clocks you are willing to be.
The two clocks
| Clock | Published rate | Source |
|---|---|---|
| People change jobs | 23% a year | ZoomInfo, 2025 |
| Mailboxes stop existing | 40% within two years | NeverBounce |
Both are usually read as annual figures, which hides how fast they operate month to month. 23% a year compounds to roughly 2% of the list per month; 40% over two years is also roughly 2% a month. Together that is about 4% of a stored list a month that stops being reachable - and because an address can be lost to both causes at once, the true combined figure is slightly below the sum, never above it.
The monthly figures are arithmetic on the two published rates, not a TAPAC measurement. The rates themselves are quoted from the sources above.
What that means per list size
The difference between a fresh check and a stored one is the published bounce gap: 2-5% on verified contacts against 10-35% for static, resold databases. On a list of 5,000 contacts re-checked quarterly, the staleness that accumulates inside one cycle is the residual decay between the last check and the send - which is exactly the part the cadence controls.
A cadence you can defend
| Situation | Re-check when | Why |
|---|---|---|
| Addresses collected for a campaign | At the moment of the find, then at the send | The check is a snapshot; the send is when it has to be right |
| List in active weekly use | Every 30 days | At roughly 4% a month of decay, a month is the point where the residual bounce is still inside the 2-5% band |
| List used a few times a year | Before every send | Between sends there is nothing to maintain - a dormant list cannot be kept warm, only re-checked |
| List untouched for a year or more | Treat as a new list: check everything | After a year the accumulated loss is on the order of a third of the file |
What the cadence costs
A check is priced per contact, not per seat: $0.10-0.50 per verified contact, pay-per-use, 100 free searches to start. Re-checking a 5,000-contact list at the low end is therefore about $500 a pass - which is the number to compare against the cost of the sends that would otherwise go to mailboxes that no longer exist, billed at the same rate as the messages that land. A per-seat tool is paid every month whether or not anything is re-checked; that is the part of the bill that does not follow the cadence.
What TAPAC returns
Contact search and mailbox verification in the same request: deliverable, undeliverable, or unknown for catch-all domains, each result timestamped and carrying the source page or profile, so the same query can be re-run later against a comparable answer.
npx -y @tapacapi/mcp # tools: tapac_find_contacts, tapac_status # or hosted: https://tapacapi.com/mcp # or REST: POST https://tapacapi.com/v1/contacts/search
Related: what a normal bounce rate looks like, cleaning a list as maintenance, and how long verification results stay valid.
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