Verify Emails Before Dunning and Renewal Reminders, So Customers Can Fix Their Card

Verify the addresses on your subscriber list before dunning and renewal reminders go out, because the email is the customer's only prompt to fix their card. If it bounces, the customer never learns the payment failed, access ends, and the loss looks like churn when it was a dead mailbox.

Why subscription lists are the risky ones

Subscribers sign up once and then sit on the list for years. Over that time:

• Work addresses die when people change jobs. The person who paid for a team plan leaves and their mailbox is closed.
• Typos made at checkout never get noticed, because receipts and a welcome email are the only mail that used to go there.
• Free-trial addresses entered quickly stay on the account after conversion.

On a marketing list a dead address is a wasted send. On a billing list it is a customer who cannot be recovered by email at all. See how fast B2B contact data decays for why this is a matter of time, not carelessness.

Step 1: Export the subscribers who will be billed

Pull the list from your billing tool: customer ID, email, plan, renewal date and last payment status. If the tool holds more than one email per account (billing contact and owner), export both. Export customer emails from Stripe shows one route, and your CRM export works the same way.

Group the list by renewal month so you can check in batches, starting with the accounts that renew soonest.

Step 2: Verify the addresses

First see what is on the list: the email list send tier splitter shows the rows with syntax errors or typo domains that need a fix before any check. Then upload the file on the verify page. Each address comes back valid, risky or invalid, with a reason. For subscription lists the most useful reasons are:

Reason	What it tells you	What to do
Mailbox not found	The mailbox is gone	Reach the customer another way and ask for a new address
No mail server	The domain no longer takes mail, often a closed business	Same, and check the account is still active
Typo domain	A slip such as gmial.com	Fix it if the correction is clear, then check again
Accepts all addresses	The domain takes any mail	Send; the mailbox cannot be confirmed
Disposable address	A throwaway used for a trial	Ask for a real address

Valid, risky, invalid and catch-all: how to read the report covers each one.

Step 3: Write to the customers who cannot be reached

For each invalid address, in order of how soon the account renews:

1. Another address on the account: a billing contact, a team inbox, or the address on the last invoice.
2. A prompt at login: a banner that asks the customer to confirm their email. It reaches the person who uses the product, which is often not the person who pays.
3. A message through the payment provider, if it can reach the customer directly.
4. A phone call for larger accounts, where you hold the number and may use it.

Keep a note on the account of what you tried. When a customer says "I never got an email", you can see what happened.

Step 4: Keep the check current

A one-off check decays. Three small habits keep it useful:

• Re-check on a schedule. How often to re-verify an email list gives a cadence by list type. For subscriptions, before each renewal cycle is a good anchor.
• Check bulk imports. After migrating billing tools or merging customer lists, verify the whole import.
• Check at the point of capture. A check on the sign-up form catches typos when the customer can still correct them. Email typo correction covers the form side.

Step 5: Look at the sending side too

Verification removes addresses that bounce. It does not make a message arrive or get read:

• Send billing mail from a domain with working SPF, DKIM and DMARC.
• Keep it plain: what failed, the amount, one button to update the card.
• Do not mix a promotion into it.
• Keep it on a transactional stream, apart from marketing. Do Gmail's sender rules apply to transactional email? explains how the big providers see the difference.

If the bounce rate on billing mail rises, read what to do after a high bounce rate.

A note on tone

Dunning is a message to a customer who has probably done nothing wrong. A card expired or a bank blocked a charge. A message that assumes bad faith loses customers. A short, calm message that shows how to fix the problem works better, and it only works if it arrives.

What this does not cover

Verification cannot tell you whether the person at a valid address is the one who pays. It does not decide how many reminders you should send or when. Check your own terms and the rules where your customers live for how payment failures and renewals must be communicated; this is not legal advice.

A small routine

Pick the accounts renewing in the next month, verify their addresses, and fix or flag the invalid ones before the billing run. Do it again next month for the following group. After a quarter every subscriber has been checked once, the dead addresses have been chased, and each billing cycle only needs the new and changed accounts checked. It is a few minutes a month, and it protects the revenue that failed payments put at risk.

Check the list

Check the subscriber list on the verify page before the next billing cycle: 100 free checks, Google sign-in, no card.