Audience and contacts
Mailchimp counts the same person twice if they sit in two audiences, and keeps charging for unsubscribes until you remember to archive them.
What people actually say
✕Mailchimp doesn't deduplicate across audiences, so the same email address in two lists counts as two billable contacts.
Source: Mailchimp KB, duplicate contacts ↗✕Subscribed, unsubscribed and non-subscribed contacts all count toward your plan total — only archived, cleaned or deleted records stop billing, and archiving is manual.
Source: Mailchimp KB, about pricing plans ↗✕Pricing bumps at every step — 500, 1,500, 2,500, 5,000, 10,000 contacts — so adding one record above your tier can push your bill up by tens of dollars overnight.
Source: Retainful, Mailchimp pricing 2026 ↗✕Between inactive-contact billing, duplicates, overage charges and paid add-ons, actual monthly spend commonly runs 20-40% above the listed plan price.
Source: Retainful, Mailchimp pricing 2026 ↗
Your contacts live in a single Postgres table you own — dedupe is a unique index on email, not a paid feature, and unsubscribed records flip a boolean instead of inflating the bill. Audiences become tags, so the same person in three campaigns is still one row. Hosting 5,000 or 500,000 contacts costs the same to run; you pay for the box, not the headcount.