How often should I verify my email list?

Verify before the first send, again if the list is more than about 30 days old, before the later steps of a long sequence, and on a regular cycle for lists you keep, set by what a sample shows.

Do I need to re-verify addresses I already verified?

Yes, once they age. A result is true at the time of the check. People leave jobs and mailboxes close, so an old deliverable result can be wrong now.

Does re-verifying cost extra?

Each check uses a credit. Duplicates and unknowns are refunded at Mail Exchange, and credits never expire, so you can buy in advance and spend them as the schedule requires.

How Often Should You Verify Your Email List?

TL;DR

Before first use, always.
Again when a list is about 30 days old and before late sequence steps (our rule of thumb, matching our workflow).
On a cycle for lists you keep, set by a sample: if a fresh sample shows more than a few percent undeliverable, shorten the interval.

A result is true on the day you got it

Verification tells you whether an address could receive mail at the moment of the check. People change jobs, companies change domains, and mailboxes close (see why lists decay), so the result ages. How fast depends on your list. There's no universal figure, and the numbers vendors publish differ. The ones that matter are the ones you measure on your own list.

A schedule by use case

You are...	Verify
Starting a cold campaign from a fresh export	Before import. Skip it if the list was verified in the last few weeks.
Reusing a list that is over about 30 days old	Again before sending.
Running a sequence over several weeks	Before the later steps, since bounces tend to rise on follow-ups.
Keeping a newsletter or CRM list	Before large sends, and on a regular cycle (quarterly is a sensible start) adjusted by sample results.
Collecting signups continuously	At entry with the API, plus a periodic list clean.

Let a sample set your interval

Rather than guess, check a random sample of 200-1,000 addresses each time. If the undeliverable share is small, wait longer. If it jumps, verify the whole list now and shorten the cycle. This is cheaper than verifying everything on a fixed timer, and the 3-day free trial at Mail Exchange cover a first sample.

Why it matters for deliverability

Sending platforms brake on bounces (Instantly pauses above 5% after 200 sends, for example), and most recommend staying around 2% or under. See how many bounces burn a domain. Google's sender guidance tells senders to cut volume if messages start bouncing, which is easier to avoid than to fix.

Keep the cost low

Credits never expire here, so buy the pack that gets the best rate and use it across re-checks.
Unknowns and duplicates are refunded. Retry unknowns later instead of discarding them.
Only re-verify rows that were deliverable or risky; undeliverable ones are already out.

Prices run from $29 for 5,000 to $1,699 for 1,000,000. See pricing.

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How often should you verify your email list?