Microsoft 365 Migration Guide: Moving from On-Premises to Cloud

The Strategic Importance of Migrating to Microsoft 365

Managing on-premises Exchange Server, SharePoint, or file server infrastructure creates a burden that demands hardware investment, licensing, patch management, and specialized personnel. Migrating to Microsoft 365 shifts this operational burden to the cloud while also providing collaboration tools (Teams, SharePoint Online, OneDrive), security features, and the ability to work from any location.

However, a poorly planned migration can lead to email outages, data loss, and user dissatisfaction. This guide covers migration types, preparation steps, and the migration process.

Choosing a Migration Method

1. Cutover Migration

• Suitable for: Fewer than 150 mailboxes
• Duration: 1–2 weeks
• All mailboxes are moved in a single pass; after the final migration, the MX record is pointed to Microsoft.
• Risk: Users may be affected during the migration window.

2. Staged Migration

• Suitable for: Exchange 2003/2007 environments
• Users are moved in batches; the legacy server continues to operate for a period.
• Not recommended for newer Exchange versions.

3. Hybrid Migration

• Suitable for: 150+ mailboxes, Exchange 2010–2019 environments
• A reliable coexistence is established between on-premises Exchange and Exchange Online.
• Users are migrated gradually while workflows are preserved.
• The most flexible and lowest-risk method; the standard approach for enterprise environments.

4. IMAP Migration

• Primarily used for migrating to Exchange Online from Gmail, Zimbra, or other IMAP-compatible systems.

Pre-Migration Preparation Steps

1. Discovery and Inventory

# Exchange ortamındaki posta kutusu istatistikleri
Get-Mailbox -ResultSize Unlimited | Get-MailboxStatistics |
  Select DisplayName, TotalItemSize, ItemCount |
  Export-Csv C:\mailbox_inventory.csv -NoTypeInformation

• Export mailbox sizes and item counts
• List distribution groups, shared mailboxes, and resource mailboxes
• Evaluate public folder usage (can be migrated to SharePoint Online or a shared mailbox)

2. DNS Preparation

• Verify the Autodiscover record
• Lower the MX record TTL value to 300 seconds during the migration week
• Prepare to update SPF, DKIM, and DMARC records

3. License Assignment

Assign licenses to users from the Microsoft 365 admin center (Exchange Online Plan 1/2 or Microsoft 365 Business/Enterprise).

4. Azure AD Connect Setup (Hybrid)

To synchronize Active Directory identities with Entra ID:

Azure AD Connect kurulumu:
1. Hızlı ayarlar (veya özel)
2. Kaynak AD: şirket.local
3. Senkronizasyon yöntemi: Parola Karması Senkronizasyonu (önerilir)
4. Hibrit Exchange özelliğini etkinleştir

Hybrid Exchange Configuration

Hybrid Configuration Wizard (HCW)

Microsoft's HCW tool automates the hybrid configuration:

1. Download and run HCW from the Exchange admin center
2. Choose the Full Hybrid option (Exchange 2013+)
3. Certificate and connector configurations are applied automatically
4. Send Connector and Receive Connector are created

Moving a Mailbox to Exchange Online

# Taşıma isteği oluşturma
New-MoveRequest -Identity "ahmet.yilmaz@sirket.com" `
    -Remote -RemoteHostName "mail.sirket.com" `
    -TargetDeliveryDomain "sirket.mail.onmicrosoft.com" `
    -RemoteCredential (Get-Credential)

# Taşıma durumunu izleme
Get-MoveRequest | Get-MoveRequestStatistics |
  Select DisplayName, StatusDetail, PercentComplete

SharePoint and OneDrive Migration

SharePoint Migration Tool (SPMT)

Microsoft's free SPMT tool enables migration from file servers and SharePoint On-Premises to SharePoint Online:

1. Download and configure SPMT
2. Source: File server share or SP On-Premises
3. Destination: SharePoint Online site URL
4. Run a pre-migration scan to identify issues
5. Start the full migration during off-hours

OneDrive Known Folder Move (KFM)

To automatically redirect users' Desktop, Documents, and Pictures folders to OneDrive:

Grup İlkesi veya Intune:
Kullanıcı Yapılandırması > OneDrive > Windows bilinen klasörlerini OneDrive'a sessizce taşı
TenantID: [Microsoft 365 Tenant ID]

Post-Migration Checklist

• Is the MX record pointed to Microsoft 365?
• Has the SPF record been updated? (include:spf.protection.outlook.com)
• Is DKIM signing enabled in Exchange Online?
• Has the DMARC policy been applied?
• Has Autodiscover been verified?
• Have all mailboxes been moved and is the legacy server ready to be decommissioned?
• Has user training been completed? (Outlook profile reconfiguration)

Common Issues and Solutions

Conclusion

A Microsoft 365 migration is a multi-phase project that requires technical preparation, user communication, and post-migration monitoring. Selecting the correct method and sequencing minimizes migration time while maintaining business continuity. As NRC Sistem, we provide end-to-end planning and implementation support for Microsoft 365 licensing, hybrid configuration, and migration projects.