In Microsoft Dynamics CRM Online, you can configure several options specifically for the Marketing feature:
By default, Microsoft Dynamics CRM Online does not allow users to send e-mail messages as campaign activities using the mail merge feature from within campaigns. If you want to enable your users to send e-mail messages using mail merge from campaigns, you can override this default setting.
If the subject line of the e-mail that your users have sent from Microsoft Dynamics CRM Online includes the campaign code and the e-mail address for the incoming e-mail matches an e-mail address for a customer record, Microsoft Dynamics CRM Online can automatically create a campaign response based on the incoming e-mail message.
Some customers may want to unsubscribe from e-mail marketing communications your organization sends them. You can configure several options specifically related to the unsubscribe feature:
When you enable your customers to unsubscribe, Microsoft Dynamics CRM Online inserts a link into each outgoing e-mail message. When the customer clicks the link, the e-mail application opens a new message with the unsubscribe information in the subject line. Next, when the customer sends the e-mail message and Microsoft Dynamics CRM Online receives it, Microsoft Dynamics CRM Online automatically sets an option in the account, contact, or lead record to prevent the person from receiving any future marketing communications from your organization.