Mail Migration
This section describes the design decisions associated with Mail Migration for system(s) built using ASD's Blueprint for Secure Cloud.
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The implementation of Exchange Online can be coupled with a migration from the existing on-premises Exchange infrastructure. If a migration is not required, the deployment is referred to as a greenfield deployment of Exchange Online. There are three migration options:
- Hybrid Migration – Often referred to as a staged migration, is where the on-premises Exchange environment is extended to Office 365 through departmental relationships or federation. During migration user mailboxes will be spread between the online and on-premises environments, this necessitates planning to ensure free/busy, calendar and mailbox sharing all continue to work.
- Cutover Migration – A cutover migration is only recommended for organisations with less than 150 mailboxes and occurs over one or a few days. During this period email access may be unavailable. Prior to the migration event, a connection between the on-premises Exchange organisation and Exchange Online needs to be established.
- PST Migration – A Personal Storage Table (PST) migration is where PST files with a mapping file are either shipped to or uploaded into Office 365. The Exchange Online instance is a greenfield deployment with no configuration required on the on-premises Exchange environment.
Design Decisions
| Decision Point | Design Decision | Justification |
|---|---|---|
| Office 365 Tenant | Single tenant | Exchange Online services will be hosted within the organisation’s secure Office 365 tenant. |
Cloud native deployments
Design Decisions
| Decision Point | Design Decision | Justification |
|---|---|---|
| Deployment Type | Exchange Online only | No migration of mail from on prem or other services. |
Hybrid deployments
Design Decisions
| Decision Point | Design Decision | Justification |
|---|---|---|
| Deployment Type | Hybrid Migration | User mailboxes should be migrated from the on-premises Exchange environment. |
Related information
Security & Governance
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Design
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Configuration
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References
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