BigEric

@Berny Apologies for the delay in getting back. Nothing I could see in the logs. I had noticed that the first attempt to connect to the POP account failed but if I clicked on ‘download’ a second time it connected and downloaded emails. I’ve made the changes you suggested (new areas of Kaspersky I’ve not been into before, and been using it every year since 2013!) and the connection works first time, every time. Weird? But resolved. Many thanks

This is a bit strange... Thunderbird (v91.5.1, 64-bit, Win 10 Pro) connects to my POP3 account but doesn't download anything. If I then pause Kaspersky (Internet Security) Thunderbird then connects and downloads emails. I then re-start (un pause) Kaspersky and....Thunderbird continues to connect to my POP3 account and download files. If I stop and re-start Thunderbird I have to go through the Pause / un-pause process again. Kaspersky is set to NOT scan encrypted connections. It is set to scan secure traffic in Mozilla applications using the Windows Certificate store. I have disabled this and it makes no difference. I have also tried setting it to use the Mozilla certificate and installed that into Thunderbird...and it makes no difference. I’ve checked that Thunderbird is a Trusted application. In summary Kaspersky is stopping the POP3 connection; I disable Kaspersky and make the connection; and when I re-start Kaspersky the connection to the POP3 account continues to work normally.