I use www.emailprivacytester.com to check on data being leaked by email providers & clients. Mailspring doesn’t leak anything while reading (only if loading remote images, but that all email clients seem to). But mailspring does leak image data as soon as you click on reply (see screenshot) - even if you haven’t sent the email. It happens with all email accounts & does not happen in Apple Mail or Thunderbird.
Checked on Mailspring v1.9.2, and this issue is still relevant and may lead to IP address leak.
BUT(!) compared to Thunderbird it performs much better, because Thunderbird leaks this data even if you just display the message in the quick view pane, which is only fixed by setting mailnews.display.html_as to “3” (as far as I know) , that makes all your HTML correspondence look ugly. On the other hand, Mailspring exposes me only if I manually press the reply button, while always keeps all my HTML emails looking good. Thus, all of a sudden, Mailspring beats its main competitor on the privacy ground.
However, if there’s anything that can be fixed, of course it should be fixed.
