If you’re anything like me and have a lot of rules in your inbox, you may be very close or already hit your limit of allowed rules.
By default in 365 your rule limit size is 64k , you can increase this with the below command:
set-mailbox -identity User@Fomain.com -RulesQuota 256kb
The limit is 256kb so you can put any value below this also.
You should now be able to create more rules without any errors J
