I'm transitioning to Zimbra from Courier/Postfix/SquirrelMail. So far, I like it a lot but haven't transitioned my full Inbox over because I have a question to ask first.
On my current (courier) setup, I use procmail to deliver messages to the proper subfolder of my Inbox based on the group the message is sent to. I have around 50 different mailing lists I'm a member of, and managing without this delivery feature is a nightmare.
I see Zimbra provides filters to do this sort of thing, which *should* work. My only concern, however, is that when I used to use SquirrelMail's filter it was extremely slow...that's why I switched to procmail in the first place. I believe the reason SquirrelMail was slow was because the filters were not applied until you opened the Inbox up through the browser, while procmail was fast because rules are applied to the message when they are delivered (so they don't queue up).
Can someone tell me which mode Zimbra's filters operate in? Do I have room for concern?