Customer suppression list: keep existing customers out of paid ads
The short answer
Build a customer suppression list from everyone who has bought in your chosen window, then upload it as an exclusion to every paid acquisition campaign. Use email and phone from all channels, refresh the list weekly, and leave lapsed customers off it if you want acquisition and winback campaigns to reach them.
Why it matters
Every existing customer shown an acquisition ad costs money for a sale you might get anyway, often with a new-customer discount attached. Suppressing them lowers cost per new customer and stops your best buyers learning that a welcome code beats paying full price.
The question to ask
Copy this into Lexi as written.
What the answer looks like
Illustrative output on sample data
Illustrative example: how Lexi answers this for a furniture retailer preparing a suppression list for Meta and Google Ads. It uses resolved customer records with hashed email and phone.
- Includes customers who bought in the past 24 months, from any channel.
- Excludes lapsed customers, who stay eligible for winback ads.
- Excludes customers who opted out of ad targeting.
What the data shows
212,000 customers qualify, and 186,000 records remain after deduplication.
What it means
Platforms match only part of any uploaded list, so the suppressed audience will be smaller than the file. Without it, part of the prospecting budget reaches people already buying.
What to do
Refresh the list weekly and compare prospecting cost per new customer before and after.
Want me to push the suppression list to Meta and Google Ads?
Frequently asked questions
How do I exclude existing customers from Facebook ads?
Upload a customer list to Meta as a custom audience, using email and phone, then add it as an exclusion in each acquisition ad set. The data is hashed before matching. Include store customers as well as online ones, and refresh the list regularly so new buyers stop seeing acquisition offers.
Why does my suppression list match fewer people than I uploaded?
Platforms can only match records to accounts they recognize, so part of any list goes unmatched. Old email addresses, work emails and missing phone numbers lower the rate. Including both email and phone for each customer, from every channel, gives the platform more chances to find a match.
Should lapsed customers be on the suppression list?
Usually not. Customers who have not bought in your lapse window are the ones acquisition and winback campaigns are meant to reach. Keep them off the suppression list, or move them to a separate winback audience, so they still see an offer while active customers do not.