Hi @JIgnacio2,
This is only possible with the transactional email add-on. This paid add-on allows sending emails without an unsubscribe link to contact regardless of their subscription status: How to Use Transactional Emails to Send Relationship-Based Emails in HubSpot
It’s not exactly what the add-on is meant for but some HubSpot customers use it that way.
Without the add-on, no, it’s not possible to send emails to unsubscribed contacts. HubSpot puts a lot of emphasis on not sending emails to contact where there isn’t a legal basis to send emails – and without the add-on above, there aren’t any ways to work around that.
Best regards!