That means I can drop to shell from Pine, run a Mairix search and pop back into Pine to view the results just by switching to the "match" folder. Eventually I'd like to add smoother integration with Pine but for now I'm pretty happy.
I just saved myself a ton of time with this command:
mairix f:company spreadsheet
That found me the spreadsheet that someone at "company" sent me last month. Using Pine's built-in searching over IMAP I probably would have spent ten minutes looking for that mail. Instead, I spent it writing this entry.
Of course it's also incredibly fast and can limit searches by date, size and several other vectors.