Can we contact prospects that already has been contacted in previous campaigns?
Yes. There are to levels of reapproaching previous prospects. You can find both of those settings under your 'Company Settings'. Keep in mind blockings through CRM integrations still apply first and foremost.
1. Reapproaching prospects who still haven't responded
If you only want to target the prospects who haven't responded then you can set how many months must have passed for these prospects to be contactable again.
2. Reapproaching prospects who have responded
Similar as the previous option, you can set how many months must have passed for these prospects to be available for contacting again.