It connects to proprietary services which makes it not an option. The same situation for Tuta Mail. We can talk after they publish their server source code. Proton is also not an option for the same reasons.
Our team created a custom notification solution and managed to implement it in an energy-efficient way, an alternative to Google’s FCM that lets us fully bypass Google’s infrastructure.
FFS, it's a calendar. It has no business connecting anywhere.
make your own: get a domain (15$ probably less for a year), get 2x tiny servers (around 10-15$ each) and deploy MX and IMAP services on your favorite OS. Takes a while to set it up but it's pretty awesome :3
I've heard that a lot of custom domains get filtered by tech giants. Have you experienced any problems like that? I agree it would be nice and self hosting it is pretty straightforward.
gmail likes to flag some of my mail as spam despite having everything set up properly (TLS, dkim, sfp, PTR) . Some businesses have improperly configured MX, so you can't be too strict on the rules or you'll need manual intervention all the time.
Overall, it works fine I have been running various domain for about 10y now. Plus it contributes to the decentralization of email \o/