Has anyone successfully set up an unsubscribe/opt-out application or know how to do this within salesforce for emails?
Also opt-in ability would be helpful too. How do I then link it into the actual email?

I tried to install Unsubscribe opt-out 1.0.2 by Salesforce Labs. It looked like the perfect application to provide opt-out ability for an email campaign.

I received the following errors that I don't know how to fix.
Problem:
unsubscribe.testUnsubscribe2();

Item:
Apex

Problem:
unsubscribe.testUnsubscribe()  
Item: Class(01p30000000CfA9)   

Detail:

System.DmlException: Insert failed. First exception on row 0; first error: REQUIRED_FIELD_MISSING, Required fields are missing: [Salutation__c]: [Salutation__c]
Class.unsubscribe.testUnsubscribe2: line 141, column 4;
System.DmlException: Insert failed. First exception on row 0; first error: REQUIRED_FIELD_MISSING, Required fields are missing: [Salutation__c]: [Salutation__c]
Class.unsubscribe.testUnsubscribe: line 110, column 4