You can have a copy of an Opt-Out captured from one of your existing Campaigns/Offers be automatically added to your Global Opt-Out List. To enable this feature, go to the settings of the Opt-Out List and enable Copy Opt-Outs to Global List under the General Settings section.
*Please note - enabling this feature will take a copy of every Opt-Out captured to the list you have this feature enabled on and add it to the Global Opt-Out List in your account. Any email records on your Global Opt-Out List will be automatically applied to every Suppression List in your account when it is downloaded by your Affiliates/Publishers.
This is NOT a common feature to have enabled. Networks/Agencies that need to share Opt-Outs between different Advertisers may have this feature enabled, BUT this is a rare use case.
If you have any questions regarding this feature, please contact us: firstname.lastname@example.org