What does HubSpot offer to separate brands?
The native tool is Brands, the current name for business units. It is a Marketing Hub Enterprise add-on: under Settings > Brands > Multi-Brand, a super admin creates each brand and HubSpot generates the Brands contact property, in which a contact can belong to several. Each brand has its own brand kit and one additional brand domain.
You can associate forms, marketing emails, pages, subscription types, campaigns, social accounts, domains, workflows, documents, quotes and invoices with a brand. Each brand sees and uses its assets, and subscription preferences are shown per brand.
What if you do not have Marketing Hub Enterprise?
It is solved with four pieces from lower tiers. Pipelines per business line: Starter lets you create them and, with Professional or Enterprise, you restrict each one to a team from Actions > Manage access. Teams and asset partitioning: templates, sequences and pipelines from Professional; forms, emails, workflows and reports in Enterprise.
Subscription types from Settings > Marketing > Email > Subscription Types, available from Marketing Hub Starter, with the brand name. And a custom multiple-checkbox Brand property on contacts, companies and deals, required when the record is created, that feeds lists, dashboard filters and sends.
How do you keep one brand's email from reaching another brand's customers?
The first barrier is the subscription type: each brand sends only to contacts subscribed to its type. The second is the exclusion list: in every send, the Don't send to field accepts lists, for example "Active customers of brand B", which stay out even if they meet the rest of the criteria.
The third is reputation. Each brand can send from its own domain connected under Settings > Content > Domains & URLs > Email Sending, with its DKIM, SPF and DMARC records. The Don't send to unengaged contacts option is on by default and protects the shared reputation.
How do you keep the full view of the customer?
The rule is one contact, many brands. A customer who buys from two brands of your group is one record with two values in the brand property and two subscriptions, not two contacts. Duplicating contacts per brand breaks email deduplication and makes it impossible to know what that customer is worth to the group.
Reports per brand are built with the brand property as a filter: one dashboard per brand and one group dashboard without a filter. Companies in Chile and Latin America with several legal entities usually also need a billing company property, separate from the commercial brand.