What we’d like to do is tie the visitor profile to email addresses from our newsletter list.
We used the pixel from the link below.
https://matomo.org/faq/how-to/faq_25454/
Adding: &uid=(Email address of recipient)
In matomo when a user comes to the site from the newsletter the visitor profile shows as the email address. When the user comes to the site later, not from the newsletter, it has the system generated user profile and not the email address.
Also looked at https://github.com/matomo-org/matomo/issues/9884 from 2016.