You might want to know which of your contacts have completed the double opt-in process and therefore have the email opt-in type Verified double.
Segment contacts who have a verified double opt-in type
To create a segment of these contacts:
Go to Audience > Segments.
Select NEW SEGMENT.
Select Blank template and enter a name for the segment, then select CONTINUE.
Drag the Data fields block into the Include contacts that match all the rules in this group dropzone.
Select [click to select a datafield].
Select Email channel opt-in type.
Expand the drop-down menu and select Verified double.
The number of contacts in the segment is displayed. Select VIEW to see the list of contacts.