Re: office365 - active directory sync

Hi Kungpow,

The DirSync and SMTP matching will work even though you do not have the Exchange on-premises server.

If Exchange isn't installed on-premises, you can manage the SMTP address value by using Active Directory Users and Computers:

a. Right-click the user object, and then click Properties.
b. On the general tab, update the E-mail field, and then click OK.

Please refer to this article and get more information and detailed steps: How to use SMTP matching to match on-premises user accounts to Office 365 user accounts for directory synchronization

Thanks,
Bourne Zhang