Sending: in Spain, for example, article 21 of the LSSI governs commercial emails. Calling a list B2B does not on its own remove these requirements.
Tracking: the AEPD and the CNIL say that tracking pixels generally need the recipient’s prior consent. A request for consent must not be used to get around the rules on sending.
In HawkOpen every campaign recipient gets a separate copy with an unsubscribe link in the footer and List-Unsubscribe headers that allow one-click unsubscribe. Checking where the list came from and what the recipients agreed to stays with you.
Where rules that require consent apply, tracking may start only after that consent has been obtained. The link in the message lets the recipient withdraw consent later.