After reviewing Google's Security Settings, Mozilla Thunderbird could no longer connect to Google's servers and retrieve any e-mails. It said that I use several less secure apps, and therefore access to gmail servers has suddenly been blocked. Nice!
I mean it's so nice to see how Google keeps working on security, but usually that also means, that one has to adjust app settings in e-mail clients to be able to get to the e-mails, stored in gmail. ... Več ... o Google e-mail -- Less Secure App -- Access Blocked