Hello @rufaidh_rismin,

Thanks for sharing your question with the Klaviyo Community!

For organization purposes, you can certainly create segments and list which are populated by users who have placed an order. However, using these lists and sending marketing emails to these users who have placed an order but have not consented to join a list or opt-in to marketing is a different story. 

Klaviyo only supports permission-based sending. This means if your contacts have not explicitly shared consent to join a list or receive marketing emails from you, we highly suggest not emailing these users as it is a violation of our Klaviyo Terms of Service, GDPR, CAN-SPAM, and other various regulations. 

Completing a purchase is not considered explicit consent. For this reason a checkbox is offered to allow your customers the option to opt-in and join your list for marketing purposes. Only customers who have completed their purchase while ensureing the checkbox to join your list are considered consenting profiles. 

I would highly suggest taking a look at some of the following resources we offer to further understand consent and how to collect consent from your users:

• What Is Consent? Express vs. Implied
• About Compliant Lists
• Guide to Collecting GDPR Compliant Consent
• Understanding Consent in Profiles

I hope this helps!

David

Look up how to do a Post-Purchase Flow.