Update: We have now released the get-etrlimits PowerShell cmdlet. This new cmdlet incorporates many of the functionalities mentioned below, but with added ease and simplicity.
For additional relat...
Updated Aug 01, 2023
Version 5.0
Blog Post
Denis_Signorelli
Microsoft
Microsoftmomurray Thank you for your feedback! You’re right, inbox rules are limited to 256 KB total for all rules, but the difference here is where it is stored, while ETR are stored in AD the Inbox Rules are stored in the user’s mailbox as MAPI property. For that reason, it’s quite complicated to retrieve the rule size, but it should be possible through MFCMAPI to find the total rules' size.
In the Inbox folder there is a property called 0x3fff0003 (PR_Rules_Size). That should represent the inbox rule total size. I’m not sure if this property is updated when you update an existing rule, but I’m sure that it’s updated when you create a new one. If you want to test it, just reduce the rule quota to the minimum allowed (32KB) and create many rules monitoring the PR_Rules_Size property. It should block you as soon as you reach 32,768KB