#nobridge
A cheap N100 or N305 mitx with more ethernet and sata ports already attached is one thing, but I wouldn’t wanna risk warranty hell with more money on the line.
Considering you are gonna add a dgpu I would look at a low tdp desktop cpu such as ryzen 7600/9600 from a trusted store instead.
https://forums.servethehome.com/index.php?threads/topton-warranty-practices.40421/
Their site works fine without allowing javascript, that way it turns into quite a simple thing too!
SnappyMail seem to be a fork of Rainloop and both Rainloop and Snappymail appear to allow multiple providers - https://snappymail.eu/
Cypht seems to be a similar solution where you selfhost a webserver that acts as a web client to external email providers - https://www.cypht.org/documentation/
I find nothing about push notifications for either of those solutions though, and I’m not sure about how much the webclients cache.
Nautilus has been simplified to death. Personally I installed Nemo and symlinked it to replace nautilus.
I never recommended the Intel N chips though. :)