Enforces secure auto-configuration and fetching from Exchange (#50)

This patch enforces `mailnews.auto_config.fetchFromISP.sslOnly` and resets `mailnews.auto_config.fetchFromExchange.enabled` to allow fetching from Exchange servers when auto-configuration is enabled.

It also resets two auto-configuration URL preferences as doing so prevented users from re-enabling this feature.

Co-authored-by: Samuel FORESTIER <[email protected]>

user.js

@@ -1152,15 +1152,17 @@ user_pref("_user.js.parrot", "9100 syntax error: this parrot is blind!");
  * Such settings require a query to Mozilla which could have privacy implications
  * if the user wishes to keep the existence of the mail provider private.
  * We also enforce (valid) SSL/TLS connections if auto-configuration happens to be enabled.
+ * If auto-configuration is re-enabled, fetching from Exchange will be allowed by default.
  * [1] https://developer.mozilla.org/en-US/docs/Mozilla/Thunderbird/Autoconfiguration ***/
 user_pref("mailnews.auto_config.guess.enabled", false);
 user_pref("mailnews.auto_config.fetchFromISP.enabled", false);
 user_pref("mailnews.auto_config.fetchFromISP.sendEmailAddress", false);
-user_pref("mailnews.auto_config.fetchFromExchange.enabled", false);
+user_pref("mailnews.auto_config.fetchFromISP.sslOnly", true);
+   // user_pref("mailnews.auto_config.fetchFromExchange.enabled", false);
 user_pref("mailnews.auto_config.guess.sslOnly", true);
 user_pref("mailnews.auto_config.guess.requireGoodCert", true); // [DEFAULT: true]
-user_pref("mailnews.auto_config_url", "");
-user_pref("mailnews.auto_config.addons_url","");
+   // user_pref("mailnews.auto_config_url", "https://live.thunderbird.net/autoconfig/v1.1/");
+   // user_pref("mailnews.auto_config.addons_url","https://live.thunderbird.net/autoconfig/addons.json");
 /* 9102: Disable account provisioning [SETUP-INSTALL]
  * This option allows users to create a new email account through partner providers.
  * [1] https://developer.mozilla.org/en-US/docs/Mozilla/Thunderbird/Account_Provisioner ***/