Migrating from Exchange 2016 to Office 365

Hi all

Currently I am working with a customer who want to move their email hosting from Exchange 2016 to Office 365.  I was wondering if it is possible to have two MX records while the migration is going on.  I want to setup the Office 365 environment up first before migrating mailboxes  The Exchange 2016 provider host multiple domains so a hybrid version is not really an option.  I am wondering what is the best way to achieve this migration.  Thanks in advance.
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timgreen7077Exchange EngineerCommented:
2 MX records would not work in this situation because you will have users in 2 different environments and the MX records points to email domains and not user email addresses. since hybrid is not an option, I would setup your O365 environment first and create the user mailboxes in the new environment. once the mailboxes are setup I would point the MX records, Autodiscover and SPF records to O365 so that the users can start getting their emails in O365. Now they are getting the email in O365, i would then export their mail from the old environment and import it into the new mailbox in O365 so that they will still have all their previous mail.

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Hi, it depends also on how many mailboxes your organization has to manage.
Also have a look at supported migration paths, it’s useful background and will help you make up your mind.
Marshal HubsEmail ConsultantCommented:
Use Exchange Deployment Assistant.


Just enter your scenario and it will give you the guidance you need.

Another one is Stellar EDB to PST Converter. The software helps you to migrate mailboxes from Exchange Server to Office 365.
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Sandeep KumarAssociate ConsultantCommented:
I agree with timgreen7077, the first part is defiantly setup of Office 365 and create the user mailboxes in the new environment like timgreen7077 said. And the second for migration needs, you can use Kernel Migrator for Exchange software, which can do migrate user mailboxes from Exchange 2016 to Office 365 flawlessly. Go through https://www.nucleustechnologies.com/exchange-migration/office-365-migration.html to know more about the process.
SysToolsData Expert - Recovery,Backup,MigrationCommented:
The best way to achieve perfect Migrating from Exchange 2016 to Office 365. First set up the Office 365 environment up first before migrating mailboxes, you can visit the helpful link: https://www.youtube.com/watch?v=DoRRkYlgTjI  for complete Setup video

Now to Migrate multiple mailboxes from Exchange EDB 2016 to Office 365 User Account. You can Download Demo Version of  SysTools Exchange to Office 365 Migration Software from here: https://www.systoolsgroup.com/exchange-to-office365-migrator.html

Some Prominent features of the tool are given below in image:
Tool FeaturesYou can also View Video of Exchange Migrator to know all details related less time:
Helpful Video Link: https://youtu.be/66kstG1xHG0
Annie RoseTech LeadCommented:
Another great tool would be the Exchange Deployment Assistant:

Just pop in your scenario and it should give you the guidance you need. Else, you could try some migration solution like; Shoviv for Office 365 and CodeTwo for Office 365 to migrate from from Exchange 2016 to Office 365 without any interruption.
WooYingAuthor Commented:
Thank you all very good information, I should have mention that this is a really small environment,  there are less than 75 users.  Also, timgreen7077 not that I do not disagree with you and I am trying to only learn here.  I am curious as why would it not work, I believe I could have two MX record one with a higher priority and then one with a lower priority.  If the mailbox is not found with the higher priority would it not check the secondary mailbox?  Again, just want to learn from you and see what am I missing point of view.  Thank you again everyone.
timgreen7077Exchange EngineerCommented:
The issue is that the MX record has nothing to do with actual mailboxes. Its the email domain that the record references, so if you have 2 MX records pointing to 2 different companies (your 3rd party hosted company and O365), if the mailbox is no longer in the 3rd party environment but it has been moved to O365, but the host 3rd party it still accepts emails for that domain, the email will just fail because recipient wont be found, it will not look at the second MX record. The 2nd MX record is used if the 1st one can't be contacted.
WooYingAuthor Commented:
timgreen7077 - Thank you, so the second MX record works as a whole and not on an individual mailbox.  I see exactly what you mean now, so with your suggestion creating the new mailbox on O365 first and then changing the MX records should work just fine in that case.  But once the MX record is reported and mail is flowing to the new email server.  Is it possible for the clients to still be connected to the old mailbox for migration or just check one last time to make sure that no emails were missed.  Thank you again for the explanation.
timgreen7077Exchange EngineerCommented:
Once you point the MX records to the new environment, you will have to wait for DNS replication. Replication can take up to 48hrs but I have never seen it take that long. It normally takes a few hours for DNS replication. Once replication is complete, all mail will start going to the new environment which will be O365. Depending on your current hosted company, all those users still should be able to access their emails or until you cut off that service. Export the emails for the users to a pst file, and then it can be imported into the new mailbox in O365. since you can't setup hybrid the export to pst will be the method to use and then import those pst files into the new mailbox you created in O365. there are also 3rd party tools that can help with getting the pst files imported for you.
WooYingAuthor Commented:
Thank you all
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