I think that in your Thunderbird account settings, the "delete emails older than 5 days" checkbox is selected"

In settings in "server configuration" I had marked "leave coopies of messages on server" 14 days. Now I changed it on 800 days. But I still don't have my all emails on website email account... I attach print screen settings in my Thunderbird. English will be better but I don't know how I can change langueage...

I add, that when I right click on "Inbox" and select "Properties" in line "Location" I have address to folder on my PC. I tried change this on: imap://krzysco9%40tlen.pl@poczta.o2.pl/INBOX but I can't... Please help me

1. Create a new account with the imap Protocol in thunderbird. 2. After it is synchronized, select and drag the necessary letters from the inbox folder of your pop3 account to the inbox folder of your imap account. 3. wait for the synchronization process to finish. 4. accept mail on other devices