User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.212 Safari/537.36

Steps to reproduce:

• disconnect from the internet
  or
• connect to a non-internet LAN,
  or
• google requires web-login to continue

Actual results:

Thunderbird shows modal pop up dialogs (s) :

1. when the calendar can't sync
2. when the calendar needs to resolve disambiguity
3. when the server requires web-login (e.g. when google's getting paranoid)

Expected results:

thunderbird could show unobtrusive notificaations;
thunderbird could show a red banner under the toolbar until the matter is solved;
thunderbird could make a yankee-doodle sound intermittently;
thunderbird could changed its theme color to red until problems resolved;
thunderbird could shout at you in German that you're not ok.

just don't block, please.

We can have it configurable (if people would like to be blocked by default, go ahead). But please let me change it in some checkbox in the settings.

Usually I just want to read mail, search something, compose an offline message; look at the calendar, etc, especially when I'm offline for any reason (there are many, if you ask)

If you are able to test, can you confirm that the fix at https://bugzilla.mozilla.org/show_bug.cgi?id=1715740#c39 helps?

Please check version 91