Following was 1 of the observation found while doing the integration and sending out emails using customer Office365 SMTP.
There is a limit on how many emails/messages one O365 user can receive or sent . As per Microsoft, receiving and sending limits are applied to combat spam and mass-mailing worms or viruses.
This limitation is at Microsoft’s end and NOT on Saviynt.
Exchange Online limits - Service Descriptions | Microsoft Learn – Microsoft Docs link for reference
Note : As per Microsoft, “Message rate limits determine how many messages a user can send from their Exchange Online account within a specified period of time. This limit helps prevent over consumption of system resources by a single sender. If a user submits messages at a rate that exceeds the limit via SMTP client submission, the messages will be rejected and the client will need to retry.”
Now as a part of campaign the expectation is we would be sending out multiple emails and this may not work as expected.
you should be able to achieve this use case by configuring the Rate Limit under SMTP configuration. Below is the documentation for your reference.