1 · The order we work in
| Layer | Who | How it is built | Used for |
|---|---|---|---|
| Warm | People who already engaged with the class: opened or clicked its email, visited its page, registered interest | HubSpot active list, synced to LinkedIn as a matched audience | The first and cheapest reach for any class |
| Look-alike | People LinkedIn judges similar to the warm list | LinkedIn Predictive audience seeded from the warm list | Widening reach once the warm list is exhausted |
| Retarget | People who watched the video or visited the site | LinkedIn video and website audiences; Google remarketing lists | A second, cheaper touch for people who showed interest |
| Cold | Defined by job title, seniority, sector, geography, or by the channels they watch | Platform targeting; YouTube channel placements | Only when the class needs reach the warm layers cannot give |
2 · The Boston audiences, as a worked example
Built 11 to 14 September 2026 in LinkedIn from HubSpot lists. Match rates are LinkedIn's; sizes are matched members.
| Audience | HubSpot source | Size on 14 Sep | Role |
|---|---|---|---|
| A, Retreat Warm | List 811: engaged with the retreat email | 358 matched, above 90% match rate | The audience both Boston ad sets run against |
| B | Broader engaged list | 956 | Fallback if A runs dry |
| C | Interest list | 757 | Reserve |
| Boston reach pool | List 817 | 3,478 | Geographic pool for a cold phase |
| Predictive from A | Seeded from A | About 25,000 while building | Added alongside A in the video ad set |
| Website visitors | Insight Tag | No signal until the tag proved active on 15 Sep | Retargeting, once it fills |
Why A and not the bigger lists: the retreat sells to people who already know HueLife, and the warm list matched well above the 300-member floor. Reach is easy to buy; relevance is not.
3 · How to sync a HubSpot list to LinkedIn
- Build an active list in HubSpot. Static list membership cannot be added by our automation, so active lists are the standard.
- Marketing, Ads, Audiences, Create audience, choose the LinkedIn account, pick the list. HubSpot pushes hashed emails.
- Wait. Matching takes a day or two. "Below 300" during that window is not a verdict.
- Name the audience for the class and the list, and record the LinkedIn audience id next to the list id in the CMO repo so the two can be reconciled later.
The same tool can push a list to Google Ads as a customer match audience. We have not used that yet; the first Google audiences are remarketing lists from the tag.
4 · Remarketing on Google
| List | Minimum to serve | State on 16 Sep 2026 |
|---|---|---|
| All visitors (auto-created from the tag) | 100 active users in 30 days for Display | Populating |
| AdWords optimized list (auto-created) | Same | Under 1,000 shown, marked too small to serve |
| Any list for YouTube remarketing | 1,000 | Not yet |
Nothing to build here until the numbers arrive. The plan on file: a $50 Display campaign to the Boston page once the visitor list clears 100.
5 · Rules
- Consent limits every audience. Visitors who decline cookies are not in any tag-based list. Warm lists from HubSpot email engagement are the exception, which is another reason to start there.
- One list per class, named for the class. Reuse the list for the email, the LinkedIn audience and the reporting.
- Do not upload CSVs to a platform. Sync from HubSpot so the audience refreshes and the source stays on record.
- Never seed a look-alike from an unrelated list. Seed it from the class's own warm list or do not build one.