Exclusions
The Exclusion tab decides who is sent to Mailchimp and groups a few behavior settings.

Exclude Market places domain emails
Customers whose email address belongs to these domains are never sent to Mailchimp, for example the anonymized addresses created by marketplaces. Separate the domains with a comma.
Customers groups
Customers in the checked groups are not synchronized.
Only subscribers
Only customers subscribed to the newsletter are sent, with their orders and carts. A customer who is not subscribed, or who belongs to an excluded group, is archived in Mailchimp when their account is created or updated.
With this option, the List tab also offers to archive at once the non-subscribed contacts already in Mailchimp: they no longer count in your plan (see Unsubscribes and billed contacts).
Double Opt-in
Mailchimp sends a confirmation email before subscribing a contact; details on the Signup forms page.
Sync carts
Sends the carts of identified customers to Mailchimp, for its abandoned cart automations. If you do not use these automations, turn it off: adding to cart gets faster.
Automatic connection of clients
The recovery link in abandoned cart emails also signs the customer in to their account. Off by default: anyone who receives the email, forwarded for instance, would open the account.
