Length of Time to Update 20,000 Contacts Using API Call
I need to synch my local database with my Constant Contact database in hopes of updating contacts who have unsubscribed from my company's email blasts. An especially helpful page I have found is located at:
It would appear that the "Add and Update up to 20,000 contacts with a single API call" is what I'm looking for (please tell me if I'm wrong in thinking this). My questions -- how much time and how much money does updating 20,000 contacts with a single API call typically take?
This is my first post in this community, and I am new to API. Any help would be greatly appreciated, and I thank you all for your time.