My spouse and I have used Thunderbird happily since 2007. It downloads two gmail accounts. Each profile has about 170,000 inbox messages that must be kept, and the computers have 2TB drives. Thunderbird runs in multiple computers. The files are now too big and slow to update, so we need to create an archival folder from 2007-2019, inbox and outbox. (The all files option mixes everything up.) They can be in local folders, but I don''t want to erase gmail files; we pay extra. And I don't want to move to outlook. What would be the best way to organize out thunderbird files? I am willing to pay a consultant or make a donation to Mozilla.