Want to know the best way to send automatic emails on contacts added to the list

Want to know the best way to send automatic emails on contacts added to the list

Hello,

Step 1 : I have created a mailing list and want to regularly and continuously add contacts to it (these would ideally be added manually via excel sheet upload).
Step 2 : I need a workflow/autoresponder to automatically send an email "immediately" to any new contact added to the list.
Step 3 : Then I need to send follow up emails based on activity/inactivity on the first email sent. (3 kinds of followups - Unopened, opened, replied)

What is the best way to achieve this? Autorespoonder or workflow and how can I set it up correctly.

Regards,
Ashwin