Zimbra server has nearly 70.000 emails stored for me till today. I use round about 350 rules (filters).
Two wishes I have:
1. When I get an email from a new employee, a new customer or similar, I have to create an new folder and a new rule.
It would be more comfortable, if there would be an opportunity to act "left-mouse-click -> create a new rule, select an option "create for whole domain" or "create for address", then automatically create a folder with name of domain or name of full address, replacing all dots by underline, create a rule-name with the folder name and use the rule.

Further incoming or outgoing emails would be ordered in the right way. So my correspondence with employees or customers are always where they should be.

2. Every day or every week there are creations of new rules. To change the order of the rules is a very dreary affair. At that time, it is better to delete a rule and create a new one, than to move a rule. An order number would be very fine: One can say for example: Move selected rule to place after rule number 56.
The reason for example: You have 60 employees and 1.000 customers... And you say, that the main rule is "move each email to the customer". If it is not an email concerning to a customer, move it to the employee. Your order of rules is first 1.000 Customers and then 60 employees. If you got a new employee, all works fine. The rule is placed at last record. But if you got a new costumer, you have to move the rules 60 times.

I hope you can help some day

Warm regards
Werner