Sync'ing recipients with users of a web app

Sync'ing recipients with users of a web app

Hello,

My client has a web app and is considering Zoho CRM and Campaigns.

One requirement is that the CRM contacts and Campaigns recipients be synchronised with users of the client's web app. I'm thinking that the developer of the web app could use your API to add contacts/recipients to CRM/Campaigns. I have a couple of questions:
  1. Should the client's web app synchronise its users with Zoho CRM or Zoho Campaigns? Could the web app synchronise directly with Zoho Campaigns, as it's unlikely that all of the users would be required to be in Zoho CRM (only key customer account holders).
  2. If the client's web app simply pushes the whole user list to Zoho on each synchronisation operation, will Zoho Campaigns intelligently block any users' addresses which have already been marked as unsubscribed?

Thanks.