Icedove autoconfig wizard gets stalled on some domains

At least on one email provider we’ve tested, it stays at “Trying common server names” for a loong time, while not even being connected to Tor anymore. No obviously relevant error message on stdout nor on the error console. Outside of Tails (38.7.2-1+b1 on sid, torified DNS fwiw, Torbirdy enabled but configured to enable the wizard) , the same domain works fine, and gives me secure protocols.

To be clear, the problem here is not exactly that Icedove doesn’t manage to guess (IMO it’s acceptable that our patchset breaks a small number of configurations): the problem is that the failure mode gives a pretty bad UX, especially given the “Stop” button doesn’t seem to do anything (and the console says “onStop called although there’s nothing to stop (re///modules/errUtils.js line 35)”).

Parent Task: #5663 (closed)

Related issues

• Related to #6154 (closed)

Original created by @intrigeri on 11486 (Redmine)