How often should I re-verify a list maintained with the VEC real-time API?

Even a clean list goes stale. People change jobs and lose their work email. Personal addresses get abandoned. Domains get bought and sold. Valid Email Checker results are accurate at the moment of verification, not forever — so re-verification needs to be a scheduled habit, not a one-off project. The right frequency depends on what kind of list you're maintaining.

Active marketing lists: every 30 to 60 days

Lists where you're actively sending campaigns to consumer or mixed B2B/B2C subscribers see the highest decay rate. A list verified clean today will be 2 to 5% stale after 30 days, mostly from churn at consumer providers (Gmail accounts going inactive, Yahoo accounts being closed). Re-verify monthly to bi-monthly to keep bounce rates under your ESP's safety thresholds.

Slow-moving B2B databases: every 90 days

B2B contacts churn through job changes, which happen on slower timescales. A B2B contact database verified clean today will see 5 to 8% turnover in 90 days, concentrated in tech and finance (high job mobility) vs healthcare and government (low). Quarterly verification catches most of the decay without burning credits unnecessarily.

Transactional-only contact stores: only on intent

If you're storing addresses purely to send order confirmations and password resets, you don't need scheduled re-verification. Sending happens against confirmed customer addresses with a recent paid transaction; the engagement signal is stronger than what verification can add. Re-verify only when you're about to switch a contact from transactional-only to marketing.

How to actually schedule it

A few patterns work in production:

• API + scheduled job. Run a nightly script that picks the N oldest-verified addresses and re-verifies them through the verify-single API. Spread the cost over the month rather than spiking on one giant batch.
• Bulk upload monthly. Export the full list, upload to bulk verification, download results, re-import. Slower but easier to reason about and audit.
• Trigger on send. Before any campaign, run the segment through bulk. This is the safest pattern for senders who don't want to commit to a fixed schedule. See the pre-campaign workflow.

Cost planning

Re-verifying a 100,000-subscriber list every 60 days is 600,000 verifications a year on that list alone. Budget accordingly. The two-bucket credit system (monthly first, PAYG second) handles steady reverification well — use the Monthly plan tier that matches your annual verification volume divided by 12, and let PAYG cover spikes.

For the industry-perspective view on cadence rather than the VEC-specific one, see how often should I clean my email list.