Potential Primary SMTP Change for Transitioned Users When Using DirSync V2

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For those administrators going through the BPOS to Office 365 Transition, there are a few Active Directory (If using Directory Synchronization) and BPOS attributes that need to be reviewed.  These attributes and values are very important in terms of how they will be seen and possibly changed once you start running DirSync V2 against Office 365.


Active Directory into BPOS uses the AD users Primary SMTP to synchronize the user and stamp their UPN and SMTP address(es).  This is performed via the DirSync V1 operation when communicating with BPOS.  Once a BPOS tenant has been Transitioned into Office 365, the administrator must uninstall DirSync V1 and install and use DirSync V2, which will run against Office 365.  DirSync V2 has different logic which now splits out the SMTP and UPN as separate and distinct attributes and values.  On-premises Active Directory UPN flows as UPN and SMTP address(es) flow as SMTP address(es).


When you run DirSync V2 for the 1st time, a Full Synchronization is performed and will find all online users and find a match with the on-premises Active Directory users, and this is called a Soft-Match, based on on-premises AD and online user SMTP addresses.  HOWEVER DirSync will compare the on-premises user’s proxyAddresses list against the online users proxyAddress list and IF the on-premises Primary SMTP address (i.e. SMTP:user@contoso.com, smtp:user.last@contoso.com) is different than the online users proxyAddress Primary SMTP, then the online user’s Primary SMTP address WILL BE CHANGED to what is set as Primary within the customer’s Active Directory.


  • On-Premises: SMTP:user@contoso.com
  • Online: SMTP:user.lastName@contoso.com

RESULTS = This user’s Primary SMTP address WILL CHANGE to user@contoso.com once DirSync V2 is run.  The end user may not realize this is happening, as they will be sending mail and not realize they are sending as a different address.  At some point a respondent may ask “Is this you?  Your email is different”, which tips them off that something has changed.


  1. After activating BPOS users, have you gone into the user’s settings and changed either their UPN or SMTP address, using either MOAC or PowerShell?
    1. If yes, then you will need to review this users on-premises Active Directory UPN and SMTP address(es) and either change the AD settings or modify the online user’s settings to align with what is set within BPOS.  The reason for this is to make sure that when DirSync V2 is run that no attributes and values will change.
    2. If no, you should still review your Active Directory and verify whether user’s UPN and SMTP align and are the same.  This is a very important task, as users will use a single name for email, login and instant messaging and aligning these properties will make it much easier for end users.

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