Is it too early to call Google and Microsoft an email cartel?

In the past week, we've learned through multiple trips to the pharmacy that two of Bunny's medications have been discontinued and alternatives have to be found. And then it was phone tag and several lost emails to her doctor before she got replacement prescriptions. And it's those lost emails that are very annoying. It turns out that the doctor's office uses Microsoft Lookout for handling all their email. I run my own email server. I've sent email to that doctor before, but that was maybe last year. This year, I guess Microsoft has decided to just simply drop emails from my server without any notification what so ever. Sigh.