Paid Social

Your retargeting lists shrink month after month

Through your own data instead of someone else's. With Customer Match, Google reaches people based on your online and offline data in Search, on the Shopping tab, in Gmail, on YouTube and across the Display Network; uploadable are email addresses, phone numbers, postal addresses and customer IDs, transferred hashed g-cmatch. For Advantage+, Meta explicitly recommends connecting your own first-party marketing data with the delivery systems meta-adv. LinkedIn maps the same logic through Matched Audiences from contact lists and website visitors li-targeting.

What we do: We settle the legal basis, cut segments by value, automate the transfer to Google, Meta and LinkedIn and report new business separately; your audiences grow from data you own instead of shrinking with browser signals.

By Svenja Müller, Strategic Team Lead Programmatic

Last updated on 5 October 2026

What it is about and when it becomes relevant

What has changed

Lists based on browser signals get smaller and age faster. What remains is data you own: purchases, inquiries, newsletters, customer IDs. Every major platform has a route for it, and all of them demand hashed transfer g-cmatch.

What it pays off for

Three things: excluding existing customers so budget flows into new business; weighting valuable groups higher; and deriving lookalike audiences from a good list instead of an arbitrary one.

What it requires

A legal basis and a process that keeps the lists current. Google names a maximum membership duration of 540 days with at least 100 updated users g-cmatch; a list uploaded once goes stale.

Common mistakes and how you spot them

Relying on website visitors alone

How you spot itThe audiences consist exclusively of visitors from the last days. They shrink visibly, and reach soon no longer suffices for a campaign of its own.

One list with no distinction

How you spot itThere is one customer list without segmentation by value or recency. Exclusions and weighting are impossible with it.

Lists going stale

How you spot itReach sinks slowly, and at some point the platform reports the list as no longer usable. Google names 540 days as the limit g-cmatch.

Legal basis unresolved

How you spot itNobody can say on what basis the addresses are used for advertising. That is to be settled before the first upload, not after.

How we go about it

Legal basis first
We only build once it is settled which data may be used on which basis. The assessment sits with you; we implement the result.
Cut segments by value
Instead of one big list, groups emerge by customer value, recency and product range, with the same logic across platforms.
Automate the transfer
The match runs regularly instead of by hand, so the membership duration does not lapse g-cmatch and the segments carry the same state everywhere.
Report new business separately
We separate new from existing audiences in the report, as Meta itself recommends meta-adv, so the contribution becomes visible.

Frequently asked questions

How do I reach audiences without third-party cookies?

Through your own data. Google offers Customer Match with email addresses, phone numbers, postal addresses and customer IDs g-cmatch, Meta recommends connecting your own marketing data meta-adv, LinkedIn offers Matched Audiences li-targeting.

How long are uploaded lists valid?

Google names a maximum of 540 days with at least 100 updated users g-cmatch. In practice, an automatic regular match pays off.

Is my customer data transferred in plain text?

No. The data is transferred encrypted, meaning hashed, before the platform matches it g-cmatch.

Can I also exclude existing customers with this?

Yes, and that is often the biggest lever. Meta recommends segments that allow a breakdown by new, engaged and existing audiences meta-adv.

Is this exactly where you are stuck?

Write to us about where it is stuck. Svenja Müller and the team will look at what is concretely behind it in your case, and tell you where the biggest lever sits.

Book a meeting

Sources

Every statement about ad products comes from the official documentation of the respective platform, with the date we retrieved it. Products change; if something looks outdated to you, write to us and we will check it.