Since we turned on okta provisioning of Office365 users, my email aliases were wiped out. How do I now add an alias to an office365 user? I am unable to do it in the office 365 admin portal as the account is synced.
Thanks for posting your inquiry in Okta Community Portal.
If your tenant is utilizing the Okta Enhanced Provisioning features with Microsoft Office 365 this is expected --when these features are used O365 is no longer the source of truth for users, it will be the Okta Universal Directory or in common cases On Premise Directories /or HR apps via Okta. So in this scenario you need to bring the proxyAddresses attribute and mapping it to O365.
This topic as well as more information on the enhanced provisioning features can be found here, https://support.okta.com/help/Documentation/Knowledge_Article/Okta-Enhancements-with-Microsoft-Office-365-Integration-1961576155#ProxyAddresses