Customers mailing list

I want to start a mailing list to our customers and I would like to get all the email addresses of our customers from the Zoho CRM...

So, I have hundreds of ACCOUNTS and each ACCOUNT has a few CONTACTS but only part of them are CUSTOMERS, that is, only part of them have the field ACCOUNT TYPE = CUSTOMERS.

How can I do it?

So:
GET ALL EMAILS FROM ALL CONTACTS FROM ALL ACCOUNTS (WHICH "ACCOUNT TYPE" = CUSTOMER)

Thank you