Let's Encrypt doesn't directly produce any client software. ACME clients are built by our community and the community builds what they feel like building. If so

Let's Encrypt doesn't directly produce any client software. ACME clients are built by our community and the community builds what they feel like building. If something hasn't been done yet, or isn't where you want it to be, that reflects community priorities, not our politics. We'd love to work more closely with Microsoft. We've been talking with Microsoft and various Microsoft community members about building great support for IIS since before Let's Encrypt launched.