I used to have Thunderbird with Google connected via POP3 with left messages on the server.
All messages are on my hard disk and I could easy separate them into different folders for years and months.
I have many email accounts, but my two email accounts with Gmail have emails since 2003 and they are really big.
Unfortunately I lost a hard disk, so all my POP3 emails (25GB !!!) are gone. To get quickly running again, I use now IMAP. However, as soon I search anything (receiver, subject) then I can go for lunch. I will not get back Thunderbird for a long time.
What is your advice to solve that problem. Use POP3 again or is there a setting in Gmail that would help? Since I use Enigmail, another client would not be an option.