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 in the bottom right and select Verified double.
Select OK.
Select SAVE.
The number of contacts in the segment is displayed. Select VIEW to see the list of contacts.