In my web application, I give the user the option to import all of his/her contacts from their email account, and then send out invites to all of these accounts or map the user to the existing accounts based on emails.
Now the question, is once all of these contacts are imported, would it be right to save these contacts back for repeated reminders, etc.?
I am quite confused here because that is the way all of the sites operate, but would that not be violation of data privacy? Is there an algorithm for this?