[paul-tharun]

MXRoute has been trying from ages to get push notifications on the IOS mail app but were getting ignored.

FastMail got access to it and it is not clear how, without any public announcement or documentation.

It is as if Apple just picked a favorite and went with it.

[Weethet]

FastMail is using JMAP, a protocol designed to support push notifications. MXRoute is stuck with SMTP/IMAP which don't support those. There might be a different reason, but I think this is probably the core issue here

[jarland]

The stock iOS Mail app does not support JMAP and therefore it has no relation to Push notifications for the stock iOS Mail app.

[admdly]

I think saying they are stuck with standard email protocols is a bit of a stretch. JMAP is not widely implemented outside of Fastmail and certainly isn’t used by Apple Mail, which actually uses a proprietary IMAP extension (XAPPLEPUSHSERVICE).