Administer Microsoft 365 Tenant

---
name: administer-microsoft-365-tenant
description: "Microsoft 365 tenant administration for Global Administrators. Automate M365 tenant setup, Office 365 admin tasks, Azure AD user management, Exchange Online configuration, Teams administration, and security policies. Generate PowerShell scripts for bulk operations, Conditional A…"
category: "DevOps & Infra"
author: community
version: "2.1.1"
icon: server
---

# Microsoft 365 Tenant Manager

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

---

## Quick Start

### Run a Security Audit

```powershell
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

```powershell
# 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)

```powershell
$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
```

---

## 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**

```powershell
# 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**

```powershell
# 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**

```powershell
$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."

---

### Workflow 2: Security Hardening

**Step 1: Run Security Audit**

```powershell
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)**

```powershell
$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**

```powershell
# 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
```

---

### Workflow 3: User Offboarding

**Step 1: Block Sign-in and Revoke Sessions**

```powershell
$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)**

```powershell
# 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**

```powershell
# 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."

---

## 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

---

## 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

---

## 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

```powershell
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