Hi @PernilleMILK,

Thanks for sharing this with us.

In terms of getting the option for “is not set” in your segment, after selecting the “birthday” property, update the data type to “Text” that will give you the option to select “is not set” for “birthday”.

After you’ve created that segment to collect users who do not have a birthday, add the birthday field to your Manage Preferences page. You’ll add this by using the “Text” option on the left-hand side after you click on “Preferences”. Ensure when you add the birthday field property, that it matches the “birthday” property already present in your account.

After the manage preferences page is squared away, simply send this segment a campaign prompting them to provide their birthday (an incentive here may be helpful such as receiving a coupon on their special day). You’ll need to insert a manage preferences tag into your welcome series email to direct them to this manage preferences page.

Thanks for being a community member.