Exporting your contacts from Mailchimp

Export your audience

1. Click Audience, then pick your audience from the Audience drop-down.
2. Click Export audience.
3. In the "Export all contacts?" pop-up, click Export CSV.

Mailchimp emails you when the export is ready. Only account Owners and Admins can export.

Just one segment?

Open the segment, then use the Segments drop-down and choose Export segment.

Which file to upload

Your download may be a ZIP file with separate CSVs inside, for subscribed, unsubscribed, non-subscribed and cleaned contacts. Upload the subscribed file. Those are the people you actually send to. The others can't be mailed anyway.

Exports stay available in Mailchimp for 30 days.

Then clean it

Upload the CSV on Clean a list. When it's done, see Removing bad addresses from your email tool to take the bad ones out of your audience.

Source: Mailchimp's export guide.