Can I recall a sent campaign?

No, there is no way to undo the sending of a campaign or recall sent emails or unopened emails. No ESPs have the capability to pull back emails that have been sent.

Depending on how severe the error is, you could send a second "Oops" email if the information itself is incorrect. 

Notes

If you view an actively sending campaign in your account, there is a very small window of time where the campaign could be paused, and then stopped. This is not a recall, but if an active campaign is paused quickly enough, the sending of some emails can be interrupted. However, any recipients that have started processing will still cycle through until they are finished. 

Please contact Support immediately if you have sent a campaign in error from your account. They will be able to evaluate the situation and provide alternatives.