This is still highly relevant and yet unanswered, as there is clear interest from the developer community, as evidenced by the numerous upvotes on this topic. Apple, please clarify: Is there a registration process for implementing XAPPLEPUSHSERVICE? Or do we need „friends at Apple“ like Fastmail stated on their blog? (Seriously?) How can third-party providers enable push notifications for iOS Mail? In light of the DMA, equal access is essential. A response would benefit many developers and users.

Progress Update: DMA Interoperability Request Entered Phase I I’m pleased to share that my request has officially entered Phase I of the DMA (Digital Markets Act) interoperability process. In the interest of transparency and collaboration, the full request is publicly accessible and can be followed here: https://developer.apple.com/file/?file=interoperability-request-tracker I hope Apple will offer a clear and well-documented path for implementing XAPPLEPUSHSERVICE in compliance with the DMA. This would be a significant step forward for developers seeking greater interoperability in push services. Feedback and insights from the community are welcome.

Apple closed the request, saying the issue wasn’t tied to a specific functionality usable inside an app. But the DMA team at the European Commission confirmed to me that the case does in fact fall under Article 6(7) of the Digital Markets Act. I was close to giving up, but then someone from Apple Developer Relations reached out directly to help figure something out. It looks like they might assign me a com.apple.mobilemail APNS topic ID — not sure when or if it’ll work yet. No idea if this will turn into a general process that other devs can use. Right now it seems pretty manual and a bit obscure. But at least Apple is aware that there’s demand for this kind of interoperability, especially after the old macOS Mail Server was sunset without a real replacement. Will see where it goes.

Final Progress Update: I’ve been provided with a working solution! Unfortunately, I can’t say which of my various communication attempts actually reached the right people — as I was contacted by Apple — so while I’m grateful, it’s still a bittersweet joy for me because I can‘t offer a clear guidance here. So I hope that Apple will soon make the process easier and more accessible for the wider community as there is considerable interest now.