Good tool/way to filter already received emails?

Does anyone know a good tool to filter email messages that are already in a (maildir) mailbox?

I know that I could simply use find+grep, but I'm searching for something with an easier syntax for defining filter rules like "if the from-header is X and the subject contains Y then move to mailbox Z".

The reason for this is that, while I already use Sieve to filter incomming mails, I would also like to create a setup where some of my mails first go to my inbox and then after (let's say) 24h are moved to a subfolder.