If your campaign contains multiple emails that will be sent to your contacts, you may want to remove contacts from the campaign once they reply.
There are 2 options you have for removing contacts from a campaign:
CANCEL: Canceling will remove them from the campaign but still allow you to send them other campaigns in the future.
OPT-OUT: This will cancel the current campaign but ALSO block them from receiving future campaigns. This is commonly used when a contact asks to be removed from your list, or is not the correct title and doesn't need to be emailed anymore.
Cancel a Campaign For a Lead/Contact
Go to "Contacts" on the left hand navigation pane and find the contact.
While viewing the contact you will see current campaigns sent in the top right of the window.
Next to the Campaign sent, click the Cancel button. You'll notice the color of the campaign name will change from black to gray to show that it has been canceled.
Opt-Out a Lead/Contact
Go to "Contacts" on the left hand navigation pane and find the contact.
Refer to the Email Opt Out field in the Contact Details section.
*Adding people to the Opt Out list in Salesforce will also block you from sending them emails via the Salesforce.com email system.