Magic Login is a service for transactional e-mails. Transactional e-mails are usually triggered by the user or other events, for instance they are sent when the user wishes to log in.
Examples of non-transactional e-mails are newsletters and marketing e-mails. You need to use a different service for those. Examples are Substack or buttondown.email.
We have to be strict about this.
Restricting our service to transactional e-mails only helps us ensure good and fast deliverability.