Increasing the maximum number of eRules 

eFiler's eRules feature uses and extends Outlook's own Rules and Categories and there is a limit to the amount of space allocated for the storage of rules. The default for an Exchange or Office 365 account is now 64KB which equates to about 150 eRules depending on how complex the criteria are and how long the paths are to filing locations. Every byte counts. However, it is relatively easy to increase this to 256KB which should be more than enough for anyone. Here's advice from Slipstick on how to do it: Assuming you are using Office 365, Exchange 2013, 2010 or 2007. To check the current setting, use the Get-Mailbox cmdlet:

Get-Mailbox username -RulesQuota

To increase the quota, use Set-Mailbox cmdlet

Set-Mailbox username -RulesQuota:256kb

Log into Office 365 using PowerShell

Enter the following commands in PowerShell to log into Office 365.

$LiveCred = Get-Credential

Enter the username and password. Note, you must have administrator rights to the server to use this. Run this cmdlet after logging in:

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri //ps.outlook.com/powershell/ -Credential $LiveCred -Authentication Basic -AllowRedirection

Then this:

Import-PSSession $Session

After you are logged in and the session imported, you can use the cmdlets. In this case, you are ready to set the RulesQuota:

Set-Mailbox username -RulesQuota:256kb