I needed to increase the Exchange rule number to 265 to make my business function properly. However, at the same time, client already had numerous rules to begin with, running the rules storage low. Is there a command that would help me figure out which rules are taking up the storage and how much?
Microsoft Exchange server, including Office 365 Exchange Online and Outlook.com, as well as on-prem Exchange servers, limit the number of rules a user can have in an Exchange mailbox. The limit is based on the total size, not number of rules, so one user might have 20 rules while another has 30.
If you mailbox rules quota is less than 256KB, your Exchange administrator can increase the limit, up to the maximum of 256KB, using the following cmdlet in the Exchange management shell to raise the limit to 256KB. See Use PowerShell to log into Office 365 Exchange if you need the complete steps to log in.
Set-Mailbox username -RulesQuota:256KB
This increased storage space allows in the neighborhood of 100 rules, or about 90 more than I want to manage in the Rules dialog.
To check the current limit for a user, open Exchange Management Shell and run
get-mailbox username | select name,rulesquota
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