Throttling Policy applied to specific MailBox not working properly

Hi,

We recently want to apply Throttling Policy to user mailbox. Our main goal is to prevent mass emailing with the MessageRateLimit parameter.

So as test purposes, we have ran these commands : 

New-ThrottlingPolicy -Name LimitMessagesSent -RecipientRateLimit 20 -MessageRateLimit 1

Get-Mailbox -resultsize unlimited | where {$_.EmailAddresses -match "test@myorg.com"} | Set-Mailbox -ThrottlingPolicy LimitMessagesSent

Get-ThrottlingPolicyAssociation test@myorg.com shows the result : 

Name                                                        ThrottlingPolicyId
----                                                        ------------------
test                                                        LimitMessagesSent

Try from Outlook and OWA to send more than 1 message in a minute.

Outlook , (Exchange account test setted) : Mailbox can send more than 1 email in a minute, looks like the policy is not applied.

OWA : Mailbox can send more than 1 email in a minute, looks like the policy is not applied.

Outlook (POP/IMAP) : The policy is correctly applied, restriction works.

Why it's not working for Outlook with Exchange setting (and not pop imap), and with OWA?

Did we miss something?

Thank you in advance for your help.

Kind Regards.