You can easily find all the subscribers who haven't had the chance to get verified via Moosend's double opt-in process, using our mighty Segments!
All you have to do is create a segment which will contain only those subscribers who are not double opt-in verified, and then send them a campaign, asking them to re-subscribe. If you have set up the double opt-in process, when they re-subscribe they'll have to give you their consent.
Let's see how this is done:
1. Click on the Mailing lists button, located on the left side of your Dashboard page.
2. Click on the name of the mailing list for which you want to create a segment. 
3. Click on the Segments option, located on the menu that appears.
4. Click on the Create New Segment button. 
5. Fill-in the name of your segment in the available text area.
Use a name that will help you identify the segment easily.
6. Click on the Add More Criteria button.
7. Choose the Verified for Double Opt-in option, from the first drop-down menu.
8. Select the option no, on the second drop-down menu.
This way all the subscribers who are not verified via the double opt-in mechanism are selected by this segment. Click on the Save segment button when you're done.
Now that you have segmented your mailing list, you can contact the non-verified subscribers by sending a cool campaign, asking them to re-subscribe to your mailing list. Every one who does will receive the confirmation e-mail you created, giving you their consent. Don't forget, your segment is dynamic! This means that every subscriber who gets verified will automatically be removed from the segment.