As a mailspring user, I appreciate how the software allows for flexible account set up, various customizations, and even third-party VPN/Tor routing, using external software (orbot-like), which is quite enough for me to be content with its functionality on everyday use.
You may know that email providers such as protonmail, cock.li and numerous others, including more private and self-hosted ones, set up tor hidden services to “provide more anonymity”. I wonder if, perhaps, email hosts that support a hidden service could be set up in some way. Maybe, a PAC plugin will suffice. I’m not familiar with the code, just a thought.
It fails to authenthicate .onion IMAP service when I run it through TOR with proxifier on Windows 10, and produces no error log but its title:
Hey @theoden8 — thanks for proposing this! Mailspring doesn’t support system proxies, but I think that you /should/ be able to route your IMAP / SMTP traffic through a VPN, bastion host, or other router by mapping localhost:PORT to your VPN, with instructions for the VPN to forward the traffic to destination:OTHER_PORT and then pointing Mailspring to localhost.
I’m not familiar with the privacy options offered by other mail providers - if we can figure this out it’d be cool to provide instructions in our knowledge base. I tried for a while to add ProtonMail Bridge support, but it turns out they implemented their own IMAP service that runs on your local machine (rather than just forwarding traffic through a VPN to a standard IMAP server), and their implementation wasn’t formatting it’s IMAP responses quite right.