It seems the only effective method right now is to retrieve all of the contact activities but even this option can not get us to what we intend!
If we retrieve contacts activities -- let's assume all of the contacts activities--, how can we distinguish activities by the campaigns they are belonging to? I mean there is no field which defines the campaign for the contact activity, is there?!!
There was another method which I personally don't think is effective, I mean the feeder method.
Even if it is effective how can we set the feeder and use it in our code? Can someone elaborate?
And about the soap API:
How can we extract the campaign activities and what type of activity does it exactly return? I think we can extract the the replied sent emails to the campaign, am I right?
Can we retrieve contact activities using the campaign id for a period of time? If yes how can we do it?