Email Opt-out box and Field-level Security
For VerticalResponse to update unsubscribe information back to your Leads and Contacts, the Email Opt out Field must be visible on both Leads and Contacts page layouts. This can only be done by a Salesforce Admin.
To add the Email opt-out box to Leads:
Go to Setup -> Customize -> Leads -> Page Layouts
Select the Layout to edit and then under Fields (it should come up by default) find Email Opt Out and drag it to the Lead Detail section. Once you’ve dropped it where you want it, click Save in the top Left corner.
To ensure this data is updated you'll need to set up, or check, the Field -Level Securities.
Go to Setup -> Customize -> Leads -> Fields
Find Email Opt Out and click the name, not the Edit link. On the next page click Set Field-Level Security and make sure it’s visible for all the Profiles. Click Save at the top to save any changes. Some profiles may not have this field visible, changing the field-level security setting will not change that.
Once this is set up, do these same steps for Contacts, choosing Contacts instead of Leads in the steps.