Yes, there are tons of ways to handle this.
Are you using WS and Lead Partitions? You need to do special things for that situation. Can you tell us more about your setup?
See ideas here:
http://www.slideshare.net/jdavidhill/marketo-email-reputation-management
http://www.marketingrockstarguides.com/subscription-management-tips-for-marketo-454/