Ian E., most deliverability is not a platform issue but users technical-know-how issues. From the email marketing perspective, most email messages ended up in spam because the sender is doing it wrong. For instance, if you are a new brand, you are expected to first build on your engagement & increase it to like 30% & above of your list, anything lesser than this will result in poor deliverability, making the algorithm of the email service provider you are using to flag your messages & all your email messages will end up in spam
