I have one single very big complaint about filters.
I've created a filter for mails to a specific distribution list, but it has little effect.
For whatever reason, when creating a filter that matches 'To' or 'Cc', it only takes into account the same information you see in the e-mail.
For example, I have my filter set so that all e-mails addressed to email@example.com get auto tagged with 'task'. However, when the e-mails come in from a few particular users, the to (or cc) headers have only a name: "Forum System". And so for whatever reason, zimbra doesn't catch, filter, and tag these mails.
Why don't filters evaluate the entire string? i.e. "Forum System <firstname.lastname@example.org>" is the actual legal address, so why does the filter routine ignore that fact?
I don't personally mind that in Zimbra, when I view the message in my box it simply says "Forum System", but the filters should take all information into account. ESPECIALLY always taking the address into accout.