[pnw_hazor]

Attaching a secondary email to an account does not grant ownership of content or IP owned by the account holder to an entity associated with the secondary email. At best it provides evidence that the account holder has [or had] a relationship with the email domain owner.

Depending on the jurisdiction, if one suffers money damages as a result of the unapproved transfer Trello or its business clients may be exposed to liability. Also, I imagine there may be privacy or consumer protection laws that could apply too even in the absence of money damages.