Of course, there are also other public DNS entries that are relevant for messaging (SPF, DKIM, etc.), but at this point we will focus on the entries shown in the table.<\/p>\n
As already mentioned, we first need to adjust the TTLs, which we temporarily change from 3600 (one hour) to 300 (5 minutes). If we do this at this stage of the migration, we can ensure that the new values are replicated worldwide when the actual cutover migration takes place.<\/p>\n
<\/p>\n
Target side preparation<\/h4>\n
In this migration example, we will not migrate the mailboxes themselves, but only all mail items such as emails, calendars and contacts. Therefore, the new, empty mailboxes can now be created on the target side.
\nDepending on the target architecture, this can be a hybrid infrastructure or just Exchange online.
\nAt this point, we only differentiate between where the new mailboxes are to be opened and how licence management can be applied.<\/p>\n
If the source site does not have a Microsoft 365 tenant, we can also enter the final mail domain in the target tenant at this point. If this is possible, the new mailboxes can already be created with the final primary SMTP address, which saves enough time in the end.<\/p>\n
<\/p>\n
Summarizing the source side information<\/h4>\n
As the migration of the mail content will take place via a 3rd party tool, we need some more information on the source side.
\nThis is summarized as follows:<\/p>\n
- \n
- List of shared mailboxes<\/li>\n
- List of room and equipment mailboxes<\/li>\n
- Authorizations for shared mailboxes<\/li>\n<\/ul>\n
Note:<\/strong> For a 3rd party migration I usually use Quest or BitTitan migration tools.<\/p>\n
So that we can export all shared mailboxes to a CSV file, the following command can be used:<\/p>\n
Get-Mailbox -RecipientTypeDetails SharedMailbox -ResultSize Unlimited | select PrimarySmtpAddress,DisplayName |\u00a0 export-csv c:\\temp\\SharedMailboxUsers.<\/pre>\n
The website “Office 365 reports<\/strong>” offers a great script for Room and equipment mailboxes. You can download it from the following link:<\/p>\n
<\/a>![](\"https:\/\/o365reports.com\/wp-content\/uploads\/2023\/12\/Export-Reports-on-M365-Room-Mailboxes-Using-PowerShell.png\")
<\/div><\/div>Export Microsoft 365 Room Mailbox Reports Using PowerShell<\/div>Utilize pre-built PowerShell script to effortlessly export 8 M365 room mailbox reports for detailed analysis and streamlined management of meeting rooms.<\/div><\/div><\/div>\nAlternatively, the following two PowerShell commands are also available:
\nRoom Mailbox:<\/strong><\/p>\nGet-MailBox -Filter '(RecipientTypeDetails -eq \"RoomMailBox\")' | Select Name,Alias |\u00a0 export-csv c:\\temp\\RoomMailbox.csv<\/pre>\n
Equipment Mailbox:<\/strong><\/p>\n
Get-MailBox -Filter '(RecipientTypeDetails -eq \"EquipmentMailbox\")' | Select Name,Alias |\u00a0 export-csv c:\\temp\\ EquipmentMailbox.csv<\/pre>\n
Finally, we need all current authorisations that are set on the shared mailboxes:
\nHere too, there are two ways in which these can be exported:<\/p>\nEither directly via PowerShell command:<\/p>\n
Get-Mailbox -RecipientTypeDetails SharedMailbox -ResultSize:Unlimited | Get-MailboxPermission |Select-Object Identity,User,AccessRights | Where-Object {($_.user -like '*@*')}|Export-Csv C:\\Temp\\sharedfolders.csv\u00a0 -NoTypeInformation<\/pre>\nOr again thanks to the “Office 365 reports<\/strong>” website:<\/p>\n
<\/a>![](\"https:\/\/o365reports.com\/wp-content\/uploads\/2020\/01\/Shared-mailbox-permission-report-powershell.png\")
<\/div><\/div>Export Shared Mailbox Permission Report to CSV using PowerShell<\/div>This PowerShell script exports Shared mailbox permission like full access, send as and send on behalf permissions to CSV file.<\/div><\/div><\/div>\n<\/p>\n
Phase 2: Prepare target<\/h3>\n
Once the new and empty user mailboxes have been created, we need to take care of the room, equipment and shared mailboxes.<\/p>\n
Creating the room mailboxes<\/h4>\n
As we have previously created an export of the various room, equipment and shared mailboxes, we can now use some of my PowerShell scripts.
\nThese scripts work in such a way that they do not need to be customized before use. We can simply start these scripts and are automatically guided through the respective process.
\nWe can use the following script for the Room Mailboxes:<\/p>\n<\/a>![\"\"](\"https:\/\/msb365.abstergo.ch\/wp-content\/uploads\/2023\/05\/GitHub-Mark.png\")
<\/div><\/div>CreateMultipleRoomMailboxes.ps1<\/div><\/div><\/div>\n<\/p>\n
Creating the equipment mailboxes<\/h4>\n
The process here is practically identical to the Room mailboxes. The only two points that are different are the corresponding CSV that is to be used and also with my PowerShell scripts it is the following:<\/p>\n
<\/a><\/div><\/div>CreateMultipleEquipmentMailboxes.ps1<\/div><\/div><\/div>\n<\/p>\n
Creating the shared mailboxes<\/h4>\n
The third import is now aimed at the shared mailboxes. As with the other two mailbox types, we have also prepared a corresponding CSV here. We can now use this with the following script to create the new empty shared mailboxes on the target page:<\/p>\n
<\/a><\/div><\/div>CreateMultipleSharedMailboxes.ps1<\/div><\/div><\/div>\n<\/p>\n
Setting the authorizations<\/h4>\n
After the shared mailboxes AND the user mailboxes have been successfully created in the target page, we now take care of the corresponding authorizations.
\nOnce again, we have prepared a CSV from the source page for this topic.
\nNow we can set the corresponding authorizations with another script:<\/p>\n<\/a><\/div><\/div>SetMailboxPermissions.ps1<\/div><\/div><\/div>\n<\/p>\n
Further information on phase 2<\/h4>\n
It is important that the exported CSV files from the source page are adapted as they are to be used for the scripts on the target page. How exactly this looks is described in the respective script itself, or alternatively in the README of the GitHub repository.<\/p>\n
<\/a><\/div><\/div>README.md<\/div><\/div><\/div>\nI will not describe public folders, etc. further in this article, or go into them in more detail.<\/p>\n
<\/p>\n
Phase 3: Mail content migration<\/h3>\n
In this phase, we now perform an initial sync between all mailboxes on the source and target side. This is not a final migration, but rather a pre-sync of the mail data up to a defined date.
\nThis helps us to migrate less content on the cutover date.<\/p>\nNote: Before the pre sync, please note whether any archive solutions are still in use on the source side. If this is the case, you must first take care of this and ensure that this content can also be migrated.
\nThere are also several ways in which this can be implemented. I will therefore not go into this point further in this article. However, it is important that this point is taken into account.<\/p>\n<\/p>\n
Phase 4: Cutover migration<\/h3>\n
For the cutover migration, it is very important that all other phases have already been successfully completed. In my example, the following points are important to note:<\/p>\n
<\/p>\n
Preparing Outlook profiles<\/h4>\n
In order for users to receive the new mailbox after the cutover, the old Outlook profile should be deleted. Once again, there are different ways to do this. I have already dealt with this topic in the past and have described three variants in more detail. You can find them in the following link:<\/p>\n
![\"\"](\"https:\/\/msb365.abstergo.ch\/wp-content\/uploads\/2023\/11\/Delete-Outlook-Cache.png\")
<\/div><\/div>![](\"https:\/\/cf-assets.www.cloudflare.com\/slt3lc6tev37\/3FQ0nr0TWKiiXvr1sipYj5\/df80437167ef2215bb09fc00ba0429fc\/dns_og.jpeg\")
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