Hi :) I recently bought a new laptop with W10 and I wanted to transfer e-mails from my old laptop (W8) to the new one. I followed the suggested steps - I copied the Thunderbird folder from the Roaming and copied it to the new one. I can see all e-mails in W10 - this is OK. But I cannot receive or send any e-mails now - there is always timeout. I can send/receive only if I run Thunderbird in safe mode. I don´t know what causes this problem, because I have no extensions or add-ons in Thunderbird. It doesn´t work even if I want to run it in safe mode and I click on "Disable all add-ons" and "Reset toolbars and controls".

There are a number of conditions for TB safe mode. If add-ons and toolbars and controls aren't a factor, try disabling hardware acceleration in Options/General/Indexing, restart TB, and see if it helps.

Disabling hardware acceleration did not solve the problem...

Hard to say why it works only in TB safe mode if you've ruled out the most common possibilities. Timeouts are usually caused by antivirus apps, and to test that, running Windows in safe mode is a common diagnostic step. Perhaps try a new profile, add an account, and see if it works in TB normal mode. Help/Troubleshooting, about:profiles, to create and run profiles.