Exchange On-Prem → M365 Mailbox Migration Batch — Cutover + Staged

“100 Mailbox’ı M365’e Taşıyoruz”

On-prem Exchange 2016 → M365. 100 kullanıcı. Hangi migration tipi?

Migration Tipleri

100 user için: Cutover uygun ama staged daha kontrollü.

Hızlı Çözüm (TL;DR) — Staged Batch

1. Exchange Admin Center (M365) > Migration > + Migrate
2. Migration endpoint: on-prem Exchange bilgileri
3. CSV ile mailbox listesi
4. Target delivery domain: firma.mail.onmicrosoft.com
5. Start batch → delta sync
6. Complete migration (her user) → MX cutover per user

Ön Koşullar

• Entra Connect sync aktif (user objects M365’te)
• Lisans atandı (M365 Business Standard+)
• Autodiscover public DNS: autodiscover.firma.com.tr → on-prem Exchange
• TLS cert: public CA + doğru SAN
• Network: on-prem → M365 outbound TCP 443, 80 açık

10:00 — Migration Endpoint

M365 EAC > Migration > Endpoints:

📸 Ekran 1 — New Endpoint
”+ Add migration endpoint”
Select migration type: Outlook Anywhere (on-prem Exchange)
Next

Exchange server FQDN: mail.firma.com.tr
Proxy server (opsiyonel): (boş)
Port: 443
Authentication: NTLM

Test: “Test connection” → green

Save.

10:10 — Migration Batch

EAC Migration > + Add Migration Batch:

📸 Ekran 2 — New batch
Name: “Staged-Batch-1”
Migration type: Remote move (hybrid) veya Cutover

Select Users: CSV Upload
EmailAddress,Password
user1@firma.com.tr,OldPassword123
user2@firma.com.tr,OldPassword456
…

(Password kolonu staged migration için — on-prem’den credential ile mailbox okunur)

Target delivery domain: firma.mail.onmicrosoft.com

Advanced:
Bad item limit: 10
Large item limit: 0

Start the migration batch automatically: ✓

Save. 15 dk içinde delta sync başlar.

10:30 — Progress İzleme

EAC Migration dashboard:

📸 Ekran 3 — Batch progress
Batch: “Staged-Batch-1”
Status: Syncing (6/100 completed)
Progress per user:
user1@firma.com.tr — Synced 78%
user2@firma.com.tr — Synced 45%
…

Average sync time: 15-45 min per mailbox (5-10 GB)

Delta sync periodic — mail-in-flight her 30 dk refresh.

11:00 — User Cutover (Complete Migration)

Her user için, batch’ten complete:

📸 Ekran 4 — Complete migration
user1@firma.com.tr sağ tık > “Complete”
Warning: “This user’s on-prem mailbox will be disabled. Outlook will connect to M365.”
Confirm

Post-complete:

• On-prem mailbox disabled (read-only)
• User Outlook restart → M365’e redirect (autodiscover)
• M365’te tam data var
• Mail flow: external mail → MX → on-prem Exchange → forward to M365 (hybrid mail flow)

Cutover Migration (Tek Seferde)

150 user altı için daha hızlı:

Migration Type: Cutover Exchange migration

• On-prem Exchange’in tüm mailbox’larını M365’e kopyalar
• MX record M365’e değiştirilir
• On-prem decommission

Downtime: MX record TTL propagation süresi (~1-24 saat).

MX Record Cutover

Staged/Hybrid bittikten sonra MX M365’e çevrilir:

Old:
mail.firma.com.tr. MX 10 mail.firma.com.tr.

New:
mail.firma.com.tr. MX 10 firma-com-tr.mail.protection.outlook.com.

DNS propagation 1-24 saat. Bu süre içinde mail’ler hem on-prem hem M365’e düşebilir — hybrid routing.

Post-Migration Cleanup

Tüm user M365’te:

# On-prem Exchange'de mailbox'ı tamamen delete
Get-Mailbox -ResultSize Unlimited | Disable-Mailbox

AD kullanıcı hesabı silme — sadece mailbox disable. User remote mailbox olarak AD’de kalır.

Yaygın Hatalar

”The connection to the mailbox failed”

Endpoint bilgileri yanlış. Test Connection rerun. Autodiscover public erişilebilir mi?

”Bad item limit exceeded”

Bozuk mail öğesi (corrupt PST item). Limit artır:

Bad item limit: 50

Veya source’ta temizle.

Outlook Client M365’e Yönlenmiyor

Autodiscover DNS hâlâ on-prem’e. Hybrid’te:

• Her user’ın targetAddress attribute’u user@firma.mail.onmicrosoft.com
• Autodiscover on-prem → redirect M365

Entra Connect attribute sync doğru mu?

İlgili Rehberler

• Exchange Hybrid Configuration Wizard
• Azure AD Connect sync

Exchange migration projesi için uzman destek? Teknik görüşme.