Hello @sabrinasee, 

Thanks for being a part of our team in helping our many Klaviyo clients! We truly appreciate it!
You can accomplish creating this list of customers who have opted out of your upcoming Mother's Day promotion in several ways.

• Option 1 which you have alluded on would be to create a general signup form asking if customers would like to join your Newsletter List and with a question of if they would like to opt-in or out of your upcoming Mother’s day promotions with this. This question you are asking of if customers want to opt-in or out of your mother’s day promotions can be mapped to collect a specific profile property such as “Mothers day Opt-in” with a value of “Yes” or “No” which you can then create segments to capture and either send your Mother’s day promotion to or sent an alternative sale to for those that selected “No”. This would be a great method to collect this information from your new subscribers. This strategy of using questions and mapping them to profile properties can be found in our Guide to Properties Help Article under the subsection of Ask Customers for Them.
  • You can also use a similar method to target existing users if you created another form with similar settings but different phrasing and whose behavior is set to target existing profiles of your Klaviyo account.
• Option 2: Similar to the first method of tagging these users with a specific profile property if they chose to opt-in or not to your Mother’s day promotion, would be to send a pre-emptive campaign email to these customers informing them of these upcoming promotions whose email also contains an Update Profile Property Link; once again asking if customers would like to opt-in to these promotions or not. This sort of strategy is alluded to in more detail and how to set up from our How to Use Links to Collect Information About Your Recipients guide. Like option 1, this approach would use segmentation to capture customers who have this profile property of opting in or opting out of these promotions to either send or not send your upcoming sale emails to.