What is a good software to organize a large IMAP account's mail?
Right now, I'm using Thunderbird filters, but ideally, I want a system where my secretary can manage the filters by herself without having to use Thunderbird filters, which are very hard to export and version control and seemingly require Thunderbird to be running continuously.
Additionally, the account is relatively large, with 70,000+ emails and 100+ arriving every day. Typical consumer grade hardware is choking just trying to download the messages in Thunderbird.
Suggestions are welcome.