Microsoft 365 Tenant Manager

Domain: Engineering - Core | Skill: ms365-tenant-manager | Source: engineering-team/ms365-tenant-manager/SKILL.md

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Microsoft 365 Tenant Manager

Expert guidance and automation for Microsoft 365 Global Administrators managing tenant setup, user lifecycle, security policies, and organizational optimization.

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Quick Start

Run a Security Audit

Connect-MgGraph -Scopes "Directory.Read.All","Policy.Read.All","AuditLog.Read.All"
Get-MgSubscribedSku | Select-Object SkuPartNumber, ConsumedUnits, @{N="Total";E={$_.PrepaidUnits.Enabled}}
Get-MgPolicyAuthorizationPolicy | Select-Object AllowInvitesFrom, DefaultUserRolePermissions

Bulk Provision Users from CSV

# CSV columns: DisplayName, UserPrincipalName, Department, LicenseSku
Import-Csv .\new_users.csv | ForEach-Object {
    $passwordProfile = @{ Password = (New-Guid).ToString().Substring(0,16) + "!"; ForceChangePasswordNextSignIn = $true }
    New-MgUser -DisplayName $_.DisplayName -UserPrincipalName $_.UserPrincipalName `
               -Department $_.Department -AccountEnabled -PasswordProfile $passwordProfile
}

Create a Conditional Access Policy (MFA for Admins)

$adminRoles = (Get-MgDirectoryRole | Where-Object { $_.DisplayName -match "Admin" }).Id
$policy = @{
    DisplayName = "Require MFA for Admins"
    State = "enabledForReportingButNotEnforced"   # Start in report-only mode
    Conditions = @{ Users = @{ IncludeRoles = $adminRoles } }
    GrantControls = @{ Operator = "OR"; BuiltInControls = @("mfa") }
}
New-MgIdentityConditionalAccessPolicy -BodyParameter $policy

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Workflows

Workflow 1: New Tenant Setup

Step 1: Generate Setup Checklist

Confirm prerequisites before provisioning: - Global Admin account created and secured with MFA - Custom domain purchased and accessible for DNS edits - License SKUs confirmed (E3 vs E5 feature requirements noted)

Step 2: Configure and Verify DNS Records

# After adding the domain in the M365 admin center, verify propagation before proceeding
$domain = "company.com"
Resolve-DnsName -Name "_msdcs.$domain" -Type NS -ErrorAction SilentlyContinue
# Also run from a shell prompt:
# nslookup -type=MX company.com
# nslookup -type=TXT company.com   # confirm SPF record

Wait for DNS propagation (up to 48 h) before bulk user creation.

Step 3: Apply Security Baseline

# Disable legacy authentication (blocks Basic Auth protocols)
$policy = @{
    DisplayName = "Block Legacy Authentication"
    State = "enabled"
    Conditions = @{ ClientAppTypes = @("exchangeActiveSync","other") }
    GrantControls = @{ Operator = "OR"; BuiltInControls = @("block") }
}
New-MgIdentityConditionalAccessPolicy -BodyParameter $policy

# Enable unified audit log
Set-AdminAuditLogConfig -UnifiedAuditLogIngestionEnabled $true

Step 4: Provision Users

$licenseSku = (Get-MgSubscribedSku | Where-Object { $_.SkuPartNumber -eq "ENTERPRISEPACK" }).SkuId

Import-Csv .\employees.csv | ForEach-Object {
    try {
        $user = New-MgUser -DisplayName $_.DisplayName -UserPrincipalName $_.UserPrincipalName `
                           -AccountEnabled -PasswordProfile @{ Password = (New-Guid).ToString().Substring(0,12)+"!"; ForceChangePasswordNextSignIn = $true }
        Set-MgUserLicense -UserId $user.Id -AddLicenses @(@{ SkuId = $licenseSku }) -RemoveLicenses @()
        Write-Host "Provisioned: $($_.UserPrincipalName)"
    } catch {
        Write-Warning "Failed $($_.UserPrincipalName): $_"
    }
}

Validation: Spot-check 3–5 accounts in the M365 admin portal; confirm licenses show "Active."

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Workflow 2: Security Hardening

Step 1: Run Security Audit

Connect-MgGraph -Scopes "Directory.Read.All","Policy.Read.All","AuditLog.Read.All","Reports.Read.All"

# Export Conditional Access policy inventory
Get-MgIdentityConditionalAccessPolicy | Select-Object DisplayName, State |
    Export-Csv .\ca_policies.csv -NoTypeInformation

# Find accounts without MFA registered
$report = Get-MgReportAuthenticationMethodUserRegistrationDetail
$report | Where-Object { -not $_.IsMfaRegistered } |
    Select-Object UserPrincipalName, IsMfaRegistered |
    Export-Csv .\no_mfa_users.csv -NoTypeInformation

Write-Host "Audit complete. Review ca_policies.csv and no_mfa_users.csv."

Step 2: Create MFA Policy (report-only first)

$policy = @{
    DisplayName = "Require MFA All Users"
    State = "enabledForReportingButNotEnforced"
    Conditions = @{ Users = @{ IncludeUsers = @("All") } }
    GrantControls = @{ Operator = "OR"; BuiltInControls = @("mfa") }
}
New-MgIdentityConditionalAccessPolicy -BodyParameter $policy

Validation: After 48 h, review Sign-in logs in Entra ID; confirm expected users would be challenged, then change State to "enabled".

Step 3: Review Secure Score

# Retrieve current Secure Score and top improvement actions
Get-MgSecuritySecureScore -Top 1 | Select-Object CurrentScore, MaxScore, ActiveUserCount
Get-MgSecuritySecureScoreControlProfile | Sort-Object -Property ActionType |
    Select-Object Title, ImplementationStatus, MaxScore | Format-Table -AutoSize

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Workflow 3: User Offboarding

Step 1: Block Sign-in and Revoke Sessions

$upn = "departing.user@company.com"
$user = Get-MgUser -Filter "userPrincipalName eq '$upn'"

# Block sign-in immediately
Update-MgUser -UserId $user.Id -AccountEnabled:$false

# Revoke all active tokens
Invoke-MgInvalidateAllUserRefreshToken -UserId $user.Id
Write-Host "Sign-in blocked and sessions revoked for $upn"

Step 2: Preview with -WhatIf (license removal)

# Identify assigned licenses
$licenses = (Get-MgUserLicenseDetail -UserId $user.Id).SkuId

# Dry-run: print what would be removed
$licenses | ForEach-Object { Write-Host "[WhatIf] Would remove SKU: $_" }

Step 3: Execute Offboarding

# Remove licenses
Set-MgUserLicense -UserId $user.Id -AddLicenses @() -RemoveLicenses $licenses

# Convert mailbox to shared (requires ExchangeOnlineManagement module)
Set-Mailbox -Identity $upn -Type Shared

# Remove from all groups
Get-MgUserMemberOf -UserId $user.Id | ForEach-Object {
    try { Remove-MgGroupMemberByRef -GroupId $_.Id -DirectoryObjectId $user.Id } catch {}
}
Write-Host "Offboarding complete for $upn"

Validation: Confirm in the M365 admin portal that the account shows "Blocked," has no active licenses, and the mailbox type is "Shared."

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Best Practices

Tenant Setup

1. Enable MFA before adding users
2. Configure named locations for Conditional Access
3. Use separate admin accounts with PIM
4. Verify custom domains (and DNS propagation) before bulk user creation
5. Apply Microsoft Secure Score recommendations

Security Operations

1. Start Conditional Access policies in report-only mode
2. Review Sign-in logs for 48 h before enforcing a new policy
3. Never hardcode credentials in scripts — use Azure Key Vault or Get-Credential
4. Enable unified audit logging for all operations
5. Conduct quarterly security reviews and Secure Score check-ins

PowerShell Automation

1. Prefer Microsoft Graph (Microsoft.Graph module) over legacy MSOnline
2. Include try/catch blocks for error handling
3. Implement Write-Host/Write-Warning logging for audit trails
4. Use -WhatIf or dry-run output before bulk destructive operations
5. Test in a non-production tenant first

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Reference Guides

references/powershell-templates.md - Ready-to-use script templates - Conditional Access policy examples - Bulk user provisioning scripts - Security audit scripts

references/security-policies.md - Conditional Access configuration - MFA enforcement strategies - DLP and retention policies - Security baseline settings

references/troubleshooting.md - Common error resolutions - PowerShell module issues - Permission troubleshooting - DNS propagation problems

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Limitations

Constraint	Impact
Global Admin required	Full tenant setup needs highest privilege
API rate limits	Bulk operations may be throttled
License dependencies	E3/E5 required for advanced features
Hybrid scenarios	On-premises AD needs additional configuration
PowerShell prerequisites	Microsoft.Graph module required

Required PowerShell Modules

Install-Module Microsoft.Graph -Scope CurrentUser
Install-Module ExchangeOnlineManagement -Scope CurrentUser
Install-Module MicrosoftTeams -Scope CurrentUser

Required Permissions

• Global Administrator — Full tenant setup
• User Administrator — User management
• Security Administrator — Security policies
• Exchange Administrator — Mailbox management