Open the antivirus UI by double-clicking its icon at the system tray (right part of the taskbar at the bottom of the window) or by searching for it in the Start menu (Cortana).The process will differ from one antivirus to another but we have decided to list out the paths to this option in the most popular antivirus tools. Either way, the problem can be solved by adding the program’s executable to the exclusions list in your antivirus.

If you are using a free antivirus, chances are that it may be blocking Mozilla Thunderbird from connecting to the Internet properly or from accessing certain files on your computer. Solution 1: Add Thunderbird to Exceptions in Your Antivirus

If you are using McAfee Internet Security, it doesn’t play alongside Thunderbird very well and you might want to replace either of these programs.

Some program or service may be interfering with Thunderbird and the only way to test this is via clean boot.

There are several problematic settings which can be turned off in Mozilla Thunderbird.Your antivirus may be interfering with Thunderbird and it may prevent it from connecting to the Internet properly.

Mozilla thunderbird help for pc