Migrating On-Prem Distribution Groups to Exchange Online in Hybrid Mode

Mark Dobrzynski 

######## Global Variables ############
Set-Location -Path $env:USERPROFILE\Documents
#Get-PSSession | Remove-PSSession
$UserCredential = Get-Credential
$ListOfGroupsToMigrate = Import-csv .\GroupMigration.csv
#######################################
$ListOfGroupsToMigrate | ForEach-Object {
$SingleGroupToMigratePSMTP = $_.GroupEmailAddress
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri http://ExhangeServerFQDN.com/PowerShell/ -Authentication Kerberos -Credential $UserCredential
Import-PSSession $Session -Allowclobber
$distrotomovedetails = Get-DistributionGroup -Identity $SingleGroupToMigratePSMTP 
$distrotomovedetails | Export-csv .\singlegroupdetailsbeforedelete.csv -NoTypeInformation
$distrotomovedetails | ForEach-Object{
    $DistributionGroupName = $_.PrimarySmtpAddress
    Get-DistributionGroupMember -Identity $DistributionGroupName | ForEach-Object{
        [PSCustomObject]@{
            DistributionGroup = $DistributionGroupName
            MemberName = $_.DisplayName
            EmailAddress = $_.PrimarySmtpAddress
           #Other recipient properties here
        }
    }
} | Export-csv .\GroupmembersBeforeDel.csv -NoTypeInformation

#########################################
$groupowner = $distrotomovedetails.ManagedBy
$GroupOwnerCorrected = $groupowner.split('/')[-1]
$GroupOwnerCorrected.ToString()
$Managedby = Get-ADuser -Filter "displayName -eq '$GroupOwnerCorrected'"
$distrotomovedetails | fl

# Extract All Email Addresses for single group one per line so you can easily add back in EXO
$addresses = @()
    Foreach ($mbx in $distrotomovedetails) {
    Foreach ($address in $mbx.EmailAddresses) {
    $obj = "" | Select-Object Identity,Alias,EmailAddress,RecipientType
    $obj.Alias = $mbx.Alias
    $obj.Identity = $mbx.Identity
    $obj.RecipientType = $mbx.RecipientType
    $obj.EmailAddress = $address.ToString().SubString(0)
    $addresses += $obj 
        } } $addresses | Export-Csv .\SingleDistroGroupsmtpaddresses.csv -NoTypeInformation
$addresses
#Remove OnPremises Group
Remove-DistributionGroup -Identity $distrotomovedetails.Identity -Confirm:$false -Verbose
Start-Sleep 120

#Create On-Premises Contact
$ExternalEmailAddress = $distrotomovedetails.Alias + "@tenant.mail.onmicrosoft.com"
New-MailContact -DisplayName $distrotomovedetails.DisplayName -Alias $distrotomovedetails.Alias -ExternalEmailAddress $ExternalEmailAddress -OrganizationalUnit "OU=Contacts,OU=Exchange Accounts,DC=lge-mdr,DC=com"
Set-MailContact -Identity $distrotomovedetails.PrimarySmtpAddress -HiddenFromAddressListsEnabled $true

#Close Session with OnPremise Exchange
Get-PSSession | Remove-PSSession -Verbose

#Connect EXO
Import-Module ExchangeOnlineManagement
Connect-ExchangeOnline -Credential $UserCredential
Write-Host -ForgroundColor Cyan "Running AAD Connect Sync"
#Remotely Run AAD Connect Delta Sync
$session = New-PSSession -ComputerName FQDNAADServer.com
Invoke-Command -Session $session -ScriptBlock {Import-Module -Name 'ADSync'}
Invoke-Command -Session $session -ScriptBlock {Start-ADSyncSyncCycle -PolicyType Delta}
Remove-PSSession $session
#Pause until AAD Connect Sync can run and Azure AD to catch up
Write-Host -ForgroundColor Green "Pausing for AAD Connect to run and then we check EXO for the group"
function Start-Sleep($seconds) {
    $doneDT = (Get-Date).AddSeconds($seconds)
    while($doneDT -gt (Get-Date)) {
        $secondsLeft = $doneDT.Subtract((Get-Date)).TotalSeconds
        $percent = ($seconds - $secondsLeft) / $seconds * 100
        Write-Progress -Activity "Sleeping" -Status "Sleeping..." -SecondsRemaining $secondsLeft -PercentComplete $percent
        [System.Threading.Thread]::Sleep(500)
    }
    Write-Progress -Activity "Sleeping" -Status "Sleeping..." -SecondsRemaining 0 -Completed
}

Start-Sleep 200
Write-host -ForegroundColor Cyan "Verifing the group  is gone from Azure AD, command will proceed once group is not showing in EXO" $distrotomovedetails.PrimarySmtpAddress
while($GetDistroFinder -ne $null){
Write-Host -ForegroundColor Cyan "Checking EXO for the old synced Distro Group"
$GetDistroFinder = Get-DistributionGroup -Identity $distrotomovedetails.PrimarySmtpAddress
Start-Sleep 10
}
Write-Host -ForegroundColor Green "Group Appears to have been removed please verify on Azure AD"
Read-Host -Prompt "Hit Enter To Proceed"

############ Recreate Group in the cloud ###########################################################################################################################################
Write-Host -ForegroundColor Cyan "Recreating the group in EXO"
#Create the EXO Distro group
New-DistributionGroup -DisplayName $distrotomovedetails.DisplayName -Alias $distrotomovedetails.Alias -Name $distrotomovedetails.Name -MemberDepartRestriction $distrotomovedetails.MemberDepartRestriction -MemberJoinRestriction $distrotomovedetails.MemberJoinRestriction -PrimarySmtpAddress $distrotomovedetails.PrimarySmtpAddress -RequireSenderAuthenticationEnabled:$false -ManagedBy $Managedby.UserPrincipalName -Verbose

#Add additional SMTP and x500 addresses to the group.
Write-Host -ForegroundColor Green "Adding SMTP and x500 Addresses Back to" $distroprimarysmtp
$EmailAddressesToAdd = Import-Csv .\SingleDistroGroupsmtpaddresses.csv
$EmailAddressesToAdd | ForEach-Object {
$AliasOfGroup = $_.Alias
$AddressToAdd = $_.EmailAddress
$x500 = "x500:"+ $distrotomovedetails.LegacyExchangeDN
$GroupLookup = Get-DistributionGroup -Identity $AliasOfGroup
Set-DistributionGroup -Identity $GroupLookup.Identity -EmailAddresses @{Add=$AddressToAdd} -Verbose
}

#Add Group Members Back to Group
Write-Host -ForegroundColor Magenta "Adding Members Back to Group"
$GroupMembers = Import-Csv .\GroupmembersBeforeDel.csv
$GroupMembers | ForEach-Object {
$Distroprimarysmtp = $_.DistributionGroup
$MemberPrimarySMTP = $_.EmailAddress
Write-Host "Adding $memberprimarysmtp to $Distroprimarysmtp"
Add-DistributionGroupMember -Identity $Distroprimarysmtp -Member $MemberPrimarySMTP
}

#Confirm Group
Get-DistributionGroup $distroprimarysmtp | Select Alias,PrimarySmtpAddress,ManagedBy,IsDirsynced,WhenCreated | FT
}