Email migration to Office 365

Microsoft Office 365 provides a set of business management and team working services, automatically managing high reliability, availability, security, and compliance.

Introduction

The project involves migrating email from the client's on-premises systems to Microsoft Office 365 services.
The need arises from the merger of a group of companies. At the time of the project's startup, each company in the group was using a different email management system: Microsoft Exchange, Oracle Messaging Server, Zimbra, Office 365.

The project aims to achieve the following client objectives:

The migration strategy included the following macro-activities:

Study of the technology and current state of:
- On-premises email systems;
- Active Directory configuration and management;
- Local anti-spam system.
Study and definition of a hybrid architecture to enable communication between on-premises systems (email servers, Active Directory, anti-spam) and Office 365.
Office 365 tenant configuration: general settings and email domain generation.
Selection of the email migration tool and adaptation of the migration method according to different source systems.
Definition of the Office package installation procedures and configuration of new client-side email accounts.
Planning and management of the email migration process for all users in the group.
Management of coexistence between on-premises systems and Office 365 during the transition period.
Post-migration support.

Application

Solution Architecture
To allow group companies to synchronize their Active Directory objects to Office 365, an AD Connect server has been configured, defining the attributes to synchronize and the exclusions (e.g., UPN with local domain).
Thanks to the synchronization, users can access Office 365 services with the same credentials used in the local Active Directory.

Migration Technology and Process
The source email systems from which to migrate are heterogeneous: Microsoft Exchange, Oracle Messaging Server, Zimbra, Office 365.
The objects to be migrated from on-premises servers to the Office 365 tenant have been identified:

Mail;
Calendars;
Contacts;
Any files.

Given the heterogeneity of the source email systems, the tool imapsync has been chosen for the migration of mail objects, and import/export strategies have been applied for the migration of Calendar objects, Contacts, and files.

Imapsync is a configurable open-source tool that allows the migration via IMAP of mailbox contents from a source system to a destination system. The tool represents the core of the solution, which includes a set of Powershell and Batch scripts aimed at configuring, automating, and parallelizing the migration of mailboxes to the Office 365 tenant.

The migration process includes the following phases (for each mailbox):

Generation of a new mailbox on the Office 365 tenant, which will host the contents of the on-premises counterpart;
Migration of the mailbox contents from on-premises systems to Office 365;
Finalization phase:
-Setting the primary email address for the mailbox;
-Blocking mail reception and enabling forwarding on on-premises systems.
-Delta synchronization: contents sent/received in the period after the first migration.
Configuration of Office 365 email accounts on user clients.

In some cases, users were using their email inbox in POP3 configuration (local management). Consequently, the server-side on-premises contents were not aligned with the actual state of the mailbox. These particular cases generated an exception in the migration process and required an export operation of the mailbox (client-side) and import to Office 365 (using the import tools provided by the cloud platform).

Heterogeneity of email clients
Employees from different companies in the group used different email clients: Microsoft Outlook, Outlook Webapp (OWA), Mozilla Thunderbird, Apple Mail. The Microsoft Outlook client was adopted by most users to leverage its capabilities and integration with Office 365. For all users who wanted to keep their original client (Thunderbird, Mail), procedures for configuring Office 365 accounts via IMAP were defined.

Benefits

The migration to Office 365 has provided several advantages:
- Avoid on-premises storage saturation and take advantage of cloud storage.
- Centralize the management of email for all domains belonging to the group using the tools provided by Office 365: Admin Portal, Exchange Online, Security & Compliance Center, etc.
- Synchronize on-premises systems (Active Directory, antispam) with the cloud.
- Utilize the troubleshooting tools provided by the Office 365 platform.
- Leverage the protection and compliance management mechanisms included in the platform.
- Availability of direct Microsoft support for issues related to the cloud platform and email client configuration.
- Expand business and teamwork using Microsoft Office tools included in the platform, such as: Office suite, SharePoint, OneDrive, Skype for Business.

Why Office 365

Office 365 is the Microsoft cloud service that provides the best business management and teamwork tools. The platform offers maximum flexibility, high reliability, robust backup policies, availability, compliance with standards, and security.
Migrating to a cloud environment allows companies to save on maintenance costs associated with managing on-premises servers, which need to be upgraded, updated, and repaired. The cloud is also responsible for managing the infrastructure: computing power, storage, network, and resource scaling.
The concept of “you pay for what you get” makes various pricing plans available based on different needs and makes it easy to add/remove features, paying only for what is used, both in terms of resources and services.
The services offered by Office 365 are always available online, anywhere in the world, and through any device.