Mailgun is transactional mail though. Not marketing mail. Mail that you want to receive like password resets, email confirmations, notifications, etc
That's what 'transactional' means... it's supposed to be used for the end or beginning of a transaction (reset password, receipt for a purchase, things like that...)
Things like friend requests are also transactional email by definition. So are those "you left your cart behind, want to complete the purchase?". That doesn't mean that you asked to receive it.
Come on, sometimes it's better to be understood than to be right. Fuck the definition.