Best way to migrate to Office365

Roland 1 Reputation point
2021-01-07T15:19:17.03+00:00

Hi,

we are a small provider changing customer emails from our Hosted Exchange to O365 (Exchange Online). Last year we did some 15 customers up to 25 mail boxes and now we want to migrate a big customer with 250 mail boxes and offices in 3 countries by the end of january.

What we did sofar....since all users are connecting with their email credentials (no AD connect) and we dont have any admin rights at the actual Hosted Exchange 2010 Server, we cannot use any migration tools. Our best practice was to KEEP THE OUTLOOK PROFILE so that the users still have their old environment (especially auto complete, etc.).

We changes the actual email from abc@test .com to aby@test .my-hosted-exchange.eu so that the users would have to change only the login name while entering Outlook from @test .com to @test .my-hosted-exchange.eu. He would still have all features and configurations of his Outlook. Than we would add a new email with his new O365 account and his adress abc@test .com (we change autodiscover before). We kept the old emails one month so that the user could copy or find important information in his old email and after this period he just had to delete the old on in Outlook. Some user we would also importa PST file but all users always had their old profile, configuration, etc.

NOW the problem ist that we did a test last week and there is a big change. Doing the same steps suddenly Outlook doenst want to add a new email and the failure message is that abc@test .com already exists although we change before the adress again to aby@test .my-hosted-exchange.eu. Outlook asks for the new login but than it keeps the old domain and user name and we are unable to add the new email.

Is there any way to force Outlook that the existing email had changed so that we can combine a new email? Would it be the same issue starting with xx.onmicrosoft.com email account and change that later to the real domain?

Any other suggestions?

Thank you very much!!

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. KyleXu-MSFT 26,271 Reputation points
    2021-01-08T02:06:18.49+00:00

    @Roland

    I would suggest you contact the Exchange administrator and do the cutover migration with him.

    After cutover migration, every user will have two mailboxes, one in Exchange on-premises(User@test .com), another in Office 365(User@test .onmicrosoft.com). Those two mailbox are in different organization which don't affect each other. You can configure both of them in the same Outlook profile.

    The Cutover migration will also help you migrate mailbox data from old mailbox to new mailbox. For more detail information about this migration method, you can have a look about this article: Migrate email using the Exchange cutover method

    The migration action is an Exchange admin job, but the Exchange server is hosted on your organization. So, I think you need to cooperate with the other party’s administrator to migrate mailboxes.


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  2. Roland 1 Reputation point
    2021-01-11T07:50:42.667+00:00

    Hello,

    thanks for your information. Unfortunately I dont see any options. It is a shared plattform with many existing users and they will not risk any problems. Sincerely I think also we dont have to knowledge rith now and since we on our site cannot push anything since we have bo admin o other access...

    Our workaround was fine for many customers. I dont understand why or how it changed so that Outlook now is caching the email information besides changing the name and the email adress....it would be easy but we dont know if we can change it now.

    The other idea would be to ADD first the onmicrosoft.com email adress, copy the PST and the day of change delete the actual @X .com account and later again add it as our @my-hosted-exchange.eu account. It would be just some steps more but we would keep the email profile and Outlook as it is.

    Thanks

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  3. Roland 1 Reputation point
    2021-01-11T12:31:59.703+00:00

    Hello,

    thanks...but again Exchange Admin is not an option and since we are responsable for the change to Office 365 we have to come with a solution for the migration end of january.

    Again, the idea was to keep the Outlook profile, than localy export the PST and import it. Also we would have one month extra access to the old email inbox so that we we unsure that we are not loosing any data.

    Problem is only the caching of the email adress and that we right now cannot add a new email adress with the real domain. We did it like that and it was a job of max. 5mins per user and that was OK and hasslefree. Users wouldnt come later and complain that their Outlook had changed.

    So again, we change for example the actual domain email@testabc.com in our online Exchange portal from the Hosted Exchange 2010 the mailbox to email@testabc.my-hosted-exchange.com. User would have to change login name on his Outlook and connect as before with all his data. We would than change autodiscover for testabc.com to O365 and simply ADD in the same Outlook profile the new Office 365 account email@testabc.com....PROBLEM NOW is that it seems that Outlook has the same information chached and we cannot add this email anymore because of the failure that it already exist -> that happened some weeks ago, before that was always possible.

    Any option to change the name in Outlook, delete the cache or do something that we can add simply as before the new O365 account?

    Thanks!!


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