Where can I find Brevos EUID (Email User ID)

I’m trying to test ad server with Brevo (in order to insert e-mail ads) and the service is asking for EUID (email user unique ID).

Where can I find Brevo email user unique ID?

Some EUID examples from other providers:

ACTIVECAMPAIGN
%SUBSCRIBERID%%MESSAGEID%

HUBSPOT
{{contact.firstname}}{{contact.hs_object_id}}

MAILCHIMP
|CAMPAIGN_UID|-|UNIQID|

PARDOT
{{Recipient.ID}}{{Current_Day}}{{Current_Month}}{{Current_Year}}

Hi @paulkl , thanks for posting on this community.

To be sure I get it well: are you asking for the contact ID, or for the ID of a recipient inside a campaign?