Data synch not updating email address

Data synch not updating email address

Before sending out a new Email Campaign (in Campaigns App), I always fetch my data from CRM to make sure I have the most current contact information. When an existing Contact has a new email address on the CRM side, I notice that the new email address is added to the Contact record on the Campaigns side, but the old one is not removed. In other words, the email address has been deleted from the CRM Contact record, but it still appears in the Campaigns App along with the new address. This means the bounce-backs are never cleaned up. I've checked all settings and haven't been able to figure why this is. When synching data, it seems the system would recognize that the old address has been replaced with the new one. What am I missing?