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Keith
Asked: 2016-09-17 10:53:15 +0800 CST

How can I stop Office 365 from adding internal addresses to mail users when synched from our on-prem server?

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I have a number of mail users (valid AD accounts with outside email addresses) and am in a hybrid Exchange environment with Office 365 and our on-prem server. The email addresses showing up in our on-prem system are just the external addresses we've assigned ([email protected]), as expected. But once the mail user gets synced to Office 365, it adds an internal address ([email protected]). Then later, when we have new users with similar names, that address has already been taken in O365 and we can't sync them. I also can't remove the extra addresses since the object is synched from on-prem, yet the additional addresses aren't assigned on-prem...

How do I stop O365 from creating internal email addresses for the mail users?

Thanks,

microsoft-office-365 exchange-2013

2 Answers

  1. I could envision a scenario where a cloud user is created and a local user and when you sync it does SMTP matching, and you are left with a synced users that then has that address.

    You may also want to check the MetaVerse in the sync client and see what attributes it has stored for the users. If you notice it's in there, for some users but not others you may have to remove those users from sync fully (so metaverse is cleared), then re-sync them.

    It is possible to make changes to cloud object, however, you first have to disable directory sync on the tenant, make your changes, then re-enable the tenant for syncing. If the email address re-appears it is almost certainly coming from on-prem.

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  2. After much back and forth on this, Microsoft said that mail users (active accounts with outside email addresses) are not supported. I have a hard time believing this but that's what they say.

    So my solution was to move the user accounts to an OU that is not synched to O365, thus deleting the user objects, and creating new contacts for each of these users so they are available in the address book. I deleted the email address from the user and added it to the contact. It took a few syncs over the course of a day for everything to fall into place and the duplicate warnings to stop but now it works great.

    Thanks for the help.

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