I've spent the last month implementing and testing IMAP support for my app [1].
It has... not been very fun.
Before we were limited to providers with a REST API, so implementing IMAP should in theory allow us to support a much wider range of email servers with a much lower support burden.
Although the protocol spec is tight, it seems like some providers randomly bug out or hang [2], respond with custom error messages, offer bespoke functionality [3], or generally don't comply with the spec in breaking ways [4].
As a result I'm more worried about this going forward than I had hoped.
I'll now also happily support anything that can help modernize email, so I'll apply to the developer program and will be watching JMAP closely.
We get ~50% of traffic from ChatGPT now, unfortunately a large amount of the features it says we have are made up.
I really don't want to get into a state of ChatGPT-Driven-Development as I imagine that will be never ending!
[1]: https://x.com/JamesIvings/status/1929755402885124154