I recently updated Avast Free 2015 v10.2.2215 to version v10.3.2223 RC2 and found a problem. After installation, I launched Thunderbird 38.1.0 and found that an error was generated when Thunderbird tried to communicate with gmail. The error was that Thunderbird could connect to pop.gmail.com. but would time out after about 10 seconds. This error was not present in the previous build of Avast Free. Therefore I uninstalled the new RC2 version of Avast and reinstalled the previous version. The error persisted which implies that the problem may have to do with something getting broken during installation. It should also be noted that accessing Gmail directly was not a problem. The only problem was accessing Gmail with Thunderbird. In addition, Thunderbird had no issue accessing my Yahoo accounts.
It was suggested, by 2 forum members, that I try replacing the Thunderbird SSL certificate with the new one in Avast. but unfortunately, that did not fix the problem. It appears that Thunderbird goes out to the pop server and connects to the server. Thunderbird then displays a message saying that it is connected to the server. It then times out after about 10 seconds or so. At this point I am a little gun shy about upgrading to the new final version. Has anyone experienced this problem with Thunderbird?