I'm using Thunderbird 108.0b1 on Kubuntu 18.04 (but that's not the issue, just for info) I need to change email supplier and I've asked the first chosen (iDENT.com) if their POP3 Email server supports the Thunderbird feature I use to control whether of not using POP3 deletion of emails from the POP3 server can be controlled; their answer was no. I think this is incorrect since I understand with POP3 this is controlled by the email client, eg Thunderbird. I know this capability is also available on Gmail which I use on my Android phone, there I set the Gmail client to not delete the emails on their server. On opening the Gmail client the emails are left on the server so that later using Thunderbird on my main Kubuntu computer I can download and file them on my machine (which is regularly backed up). My question is: am I right and whether or not under POP3 emails can left on, or deleted from the server, can be controlled by the client and therefore their POP3 server can so be controlled?