A drip campaign is a sequence of emails (the number of emails is up to you!) that you write and that we send through your email address at the times scheduled by you.
How many emails should a drip campaign contain?
The number is up to you but we generally recommend sending between 3 and 5 emails.
What happens when I add prospects to a campaign that is already running?
A campaign isn't tied to a prospect or to a list. Whenever you add a prospect to a campaign, they will get the first email, then the second, and so on... It means that you don't need to wait until you have enough prospects to launch a campaign since you can just add them as you go and they will get the messages in the right order.