Do you mean IP lawsuit's against Matrix itself?
There's not much that Matrix can do to defend against that, except for strategic marketing with the purpose of achieving a large distributed userbase. If Gmail had existed in 1990, we would not have a decentralized e-mail network today. If Gmail had got into a position where they served 99% of all e-mail users, they would've pulled the plug on mail delivery to third-party mail servers and e-mail as we know it would've been dead.
Not that I'm glad that most people I email with use gmail, since I'm precisely hosting my mails to escape Google (well, this is one of the reasons).
I cannot say that for Microsoft. After a long discussion with them, I think I'm not systematically landing in my recipients' spam folder anymore, but I'm still not very confident. Microsoft, please fix your filters! If I already exchanged with somebody in a two-way direction several times, my mails should not land in their spam folder anymore, especially if they explicitly marked me as not spam (even more if they added me to their contact list), and if you observed only legitimate mails for months or even years from my IP/domain, my mails should not be treated as spam by default even for new recipients, right? Good and reasonable filters are important for internet neutrality, where small providers can exist.