Moving between email marketing platforms: export, consent and checks

Moving a list between email platforms is mostly about keeping each person's status intact. The file carries addresses and some fields; consent, unsubscribes and suppressions have to be carried on purpose, because importing everyone as subscribed turns people who opted out into recipients. Then there is the work no file carries: automations, templates, forms, integrations with your shop and the sending domain's authentication, each of which you rebuild and test before the first real send.

There is no fixed cost for this, because it depends on how many subscribers, automations and integrations you have. The two vendors' pages we read, Mailchimp's export page and Klaviyo's consent-import page (both on 2 November 2026), show the pattern: export every status, not just the active list; keep the opt-in evidence you have; and import with the destination's consent setting chosen deliberately. The pricing consequences of moving are covered in our guides to Mailchimp pricing by contact volume, Klaviyo pricing by active profiles and email marketing pricing units.

Read this as a list of what you must save separately. The signup source is not in the export, so if you rely on it as evidence of where a person subscribed, record it before you leave. Engagement metrics (opens and clicks) are not in the audience export either; the page points to a separate campaign report export, so decide whether you need that history in the new system or only as an archive. The 30-day availability means you should download every file and store it yourself. The page states no maximum number of contacts.

Klaviyo's help page on importing consent shows why the choice matters. For SMS consent it describes three consent-status values in a column: subscribe (the person is opted in), unsubscribed (removes consent for that type) and never subscribed (leaves existing consent unchanged). Where the file has neither a consent-status column nor a timestamp, the import asks you to confirm SMS consent, and a blank cell leaves consent unchanged unless a timestamp is given. For email the page says to select Email under "Did these contacts subscribe to messaging?" only if the contacts also gave email marketing consent, and to use email as the first column when every contact has an address. For SMS it also says that if a profile opted out after an imported consent timestamp, SMS consent will not be re-added, and that you can only import consent for countries where Klaviyo SMS is available. The page does not describe email-consent column formats or proof of consent, so check the destination's current documentation for those.

Moving can change what you pay because platforms count differently. Our email pricing guide, from the vendors' help pages read on 29 October 2026, records that Mailchimp counts subscribed, unsubscribed and non-subscribed contacts, while Klaviyo prices by active profiles reachable by email. So the number you are billed on at the old platform may be larger than the list you import, and the destination's price should be read at the size you will actually hold. For the arithmetic see Mailchimp pricing by contact volume and Klaviyo pricing by active profiles; for Brevo, which prices by emails, see Brevo vs Mailchimp.