A question about requirements from other ISPs

While there isn’t any specific indication of other ISPs doing the same, the email deliverability landscape is visibly changing. As Gmail, Yahoo, and Microsoft already consist of the top mailbox providers for many senders, we can only assume that other ISPs will eventually follow suit. As such, it’s imperative to ensure that not only are we following the basic requirements, but also looking forward to implementing best practices, should they become requirements as well in the future.