A Mailchimp audience is one big pool with tags and segments layered on top, so the file you export is every subscriber you have rather than a tidy campaign list. Expect the archive to contain people who joined through a landing page in 2019, a Shopify pop-up last month and a paper form somebody typed up by hand.
Getting the addresses out of Mailchimp
Audience, then Manage audience, then Export audience. Mailchimp emails a zip with one CSV per status, and the Subscribed file is the one to verify.
Before the import, always. Mailchimp bills on audience size and its compliance team judges you on the first campaign, so an address that fails is charged twice: once on the invoice and once against a reputation you have not built yet.
What Mailchimp does with the file you bring back
The import rules decide what a re-import actually changes, which is worth knowing before you upload.
The short version
- Mailchimp matches on email address and updates existing contacts rather than duplicating them, so a re-import of a cleaned file is safe.
- Every contact counts toward your billing tier, including ones that will bounce, which makes pre-import verification a direct cost saving.
- Previously cleaned addresses cannot be re-added by import. Mailchimp blocks them permanently, which is the correct behavior and surprises people.
- Import with a tag naming the source and the date, so the next bounce cluster is traceable to a batch.
The mistake to avoid
Some addresses come back unresolved, and that is a fact about the receiving server rather than a gap in the check. We label those and never bill for them. What that means, and why roughly 28% of business addresses land there, is set out on our page about catch-all domains.
Questions people ask
Does Mailchimp verify addresses at import?
No. It checks the format and imports anything that looks like an address. The first real test happens when you send, and any failure at that point is charged to your sending reputation.
Will verifying my list lower my Mailchimp bill?
It can. Billing counts subscribed contacts, so removing addresses that would bounce before importing them keeps you off a higher tier for longer.
What about catch-all addresses?
Nobody can confirm a mailbox on a catch-all domain, so we label them rather than guessing. Import them into a separate Mailchimp segment and judge them by whether they engage.