Mailchimp is a web-based broadcast email application, on this platform you can create campaigns which can later be sent to your existing customers.
Currently DealPOS has been integrated with Mailchimp so you don't need to input customers from dealpos to Mailchimp manually, because all of that can be done automatically.
Please follow this article to get API MailChimp for your DealPOS Account.
Step 1. Go to Mailchimp and Try to Sign In
Step 2. Go to Profile Menu
Step 3. Go to Extras - API Keys
Step 4. Click Create A Key Button to Show the API Key
People also read these articles :
To Integrate DealPOS with MailChimp : Integrating DealPOS with MailChimp
To Upload DealPOS Contact to MailChimp : Upload Contact from DealPOS to MailChimp
To Sync DealPOS Inventory to Shopify : Sync Inventory DealPOS to Shopify