Each of your contacts has an 'Opt-in type' contact data field, which contains the opt-in type of that contact.
Segmenting contacts who have a verified double opt-in type
- Go to Contacts > Segments.
- Select NEW SEGMENT, and enter a name for the segment.
- Drag the Data fields block into the drop area titled 'Include contacts that match all the rules in this group'
- Select the rule and select Opt-in type from the contact data fields list.
- Expand the drop-down menu and select Verified double.
- Select OK.
- Select Save
- Select Generate count
The number of contacts in the segment is displayed.
Find out more about segmentation