Verify Your List Before a Customer Survey or NPS Send

Verify the list before a customer survey or NPS send, so the response rate means something and the survey does not bounce into your sender reputation. An undelivered survey is not a "no response". It is a missing measurement.

Why bounces distort a survey

A survey sent to 10,000 customers with 600 bounces reaches 9,400. Suppose 940 answer. The response rate is 10% against the people who got the email, and 9.4% against the original list. Neither number is wrong, but they are different, and if you compare it to last quarter's rate on a cleaner list you will think customers have become less engaged.

There is a second effect. Dead addresses are not spread evenly. Customers who have left, moved jobs or stopped using the product are likelier to have a closed mailbox. A survey that cannot reach them leaves out the most useful opinions you could have had, and the results lean toward the happy and active.

Step 1: Choose who gets the survey and export them

Decide the audience before the list: all customers, one plan, accounts that used a feature, or accounts that churned in the last quarter. Export their addresses with a customer ID and the field you will segment on. For churned customers, verify closed-lost and churned contacts before a win-back covers the older, deader end of the list.

Step 2: Verify the list

First see what is on the list: the email list send tier splitter separates role addresses and rows that need a fix from named people. Then upload the file on the verify page. Each address returns valid, risky or invalid with a reason. A feedback list is usually a list of people who once signed up, so expect some:

• Mailbox not found from people who left their company.
• Typo domains from sign-up forms, which you can often correct. Find typo domains like gmial.com in a list shows how.
• Role addresses, such as info@ or accounts@, where one person may not see the survey. For a customer feedback survey, a shared inbox answer is a weak signal, so you may want these in their own segment.

Email verification statuses explained covers every result.

Step 3: Split the list and send in order

Group	Send?
Valid	Yes, first
Risky, accepts all addresses	Yes, in a second batch, and watch the bounces
Role address	Send if the survey is addressed to the account; otherwise skip
Invalid	No. Suppress

If your survey tool lets you set a send time, send the valid rows when your customers are most likely to read, not when it is convenient to you. For the batch order, plan the send order for a verified list has the full routine.

Step 4: Count the response rate against delivered mail

After the send, do three sums:

1. Delivered = sent minus hard bounces.
2. Response rate = responses divided by delivered.
3. Unreachable share = invalid rows divided by the original list.

Report all three. The unreachable share is a finding in its own right: if one in ten customers cannot be emailed, that is a product problem as much as a list problem.

Step 5: Reach the unreachable some other way

If the feedback of a customer group matters, such as large accounts or churned ones, use another channel for the invalid rows: another contact on the account, an in-app prompt, a short call. Do not fill the gap by emailing a guessed address.

Check your own list for bias

Before you read the results, compare the people who answered with the list you sent to. If only your newest customers answered, or only one region, or only the plan with the most users, the headline score tells you about them and not about everyone. A response bias note beside the score is more honest than a clean number.

Keep the survey from hurting your sender reputation

A feedback send goes through your usual platform. Its bounces, complaints and unsubscribes count like any other mail's.

• Verify before sending, as above.
• Include an unsubscribe link if the survey is sent by your marketing tool; do not hide it.
• Do not send the same survey to the same person twice in a short window. Use the platform's suppression for people who already answered.
• Watch the first few hundred, and pause if the bounce rate is above about 2%. Email bounce rate benchmarks gives the thresholds with their sources.

Clean your list before a campaign: the 8-step checklist is the general version of this routine.

What verification does not decide

It does not decide whether your survey is good, how long it should be or whether a customer wants to answer. It makes sure that the ones who might are reachable.

A worked example

A list of 8,000 customers is checked before an NPS send. 7,200 come back valid, 500 risky and 300 invalid. You send to the 7,200, then the 500 a day later, and suppress the 300. Of 7,700 delivered, 770 respond: a 10% response rate. Against 8,000 it would read 9.6%. Reporting the first number with the unreachable share of 3.75% beside it tells the reader exactly what was and was not measured.

Check the list

Verify the survey list on the verify page before you send: 100 free checks, Google sign-in, no card.