Hi there @caitlinbmarketing,

Welcome to the community and thanks for posting your question here.

Looking into your issue, you can retrieve these missed sign ups with a segment. One piece you will need is the $source on their profile, this displays the exact form they used. You can find this on any profile on the right hand side.

Once you have that $source defined you can create a segment like this...

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If you have an example of someone that hasn't made your list, but was sent an opt in message, then you should be able to get the source and plug into a segment. That will pull a list of people who qualify, from there you can pull a CSV file of the contacts or send a campaign to the segment to opt in. You can create a campaign to send to just that segment that you pulled. Our guide to creating segments is below, this will walk you through setting this up: Guide to Creating Segments.

Also to note in your question you mention a “list segment.” As a piece of info for going further with your use in Klaviyo, it would be best to Understand the Difference Between Lists and Segments. More info on that can be found here:

Hope this helped!
Alex

Thank you @alex.hong ! This did the trick!!! You’re a lifesaver!

Glad I could help @caitlinbmarketing ! Have a great day :)