We are aware and track delivery. There has been continued new servers added and warmed to improve delivery.
For the referral email:
This is a very adversarial space, we have constantly enhanced email validations to avoid Russian bots that tag us as spam to decrease delivery. I was the one that personally sent the referral email and the list was built from a query of verified emails (people that clicked on the verification) specifically to avoid reputation damage.
Thank you for the report! Just a heads up that our team is made mainly of senior engineers with an average of +30y of age and +10y of professional experience, this kind of post just takes off our time to reply. We would appreciate much more if you use your skills to find bugs or vulnerability in the deploys or give product suggestions.
For the people receiving at SPAM, you can help improving our email delivery by marking that as not SPAM!