Launching ElectronMail causes all accounts to be simultaneously logged in. The login timings would create a pattern that makes it trivially easy to correlate the identities. Issue #113 is only partially solved by stream isolation.
The workaround is quite ugly. Since the settings directory is hard-coded, one must have a separate settings directory for each account and then have a script that links $HOME/.config/electron-mail to the relevant directory before each login of one account, also taking care that only one instance runs at a time.
The fix is to offer a setting whereby all tabs are logged-out when EM is launched, and that they only login when the tab is clicked.