block 'bulk' outbound mail

[Taen keren]

hi 

Is there a way in EXO / O365 to prevent (compromised) accounts sending out 10000 emails? 

[#2]

Hi Taen

The mailbox will be disabled automatically by Exchange Online if it were to send out a lot of mail in a short amount of time as this is indicative of spam and malicious behaviour.

See article

https://docs.microsoft.com/en-us/office365/securitycompliance/outbound-spam-controls

Hope that answers your question

Best, Chris