If your Sage CRM system has been configured for Outbound email AND users have 365 accounts, then whenever a new CRM user gets added, whomever manages your MS Exchange must remember to go into the Exchange Admin Center and enable the user’s email address to have either SEND AS or SEND ON BEHALF rights for the crm@ address that was used to configure outbound email in Sage CRM.
This is a task for your IT Team or whomever manages your Exchange. The email address crm@ is the single address used by Sage CRM users to send emails out.
You might also want to check the other user email accounts to ensure they also have these delegation rights.
