What is Office 365 migration?

Office 365 migration is the process of moving organizational data — mailboxes, public folders, archives, SharePoint, OneDrive, and Teams — into Microsoft 365, out to another platform, or between two tenants. EdbMails Office 365 Migration Software supports all of these scenarios.

How can I migrate to Office 365 using EdbMails?

The whole Office 365 migration process using the EdbMails Office 365 Migration Tool is one of the simplest there is – just connect to your source and target servers and let it do its work. Step 1: Download and install EdbMails. Step 2: Connect to the source using a global administrator account. Step 3: Choose which mailboxes and folders to migrate. Step 4: Connect to the destination server and map the mailboxes. Step 5: Begin the Office 365 migration process.

What are the reasons for migrating to Office 365?

Most teams move to Office 365 for some combination of these: Cost savings: Less spent on on-premise hardware, fewer painful upgrade cycles, and ongoing maintenance becomes someone else's problem. Scalability: Size your environment up or down as the business shifts. Accessibility: Mailboxes, documents, and apps reachable from anywhere, on whatever device the user happens to have. Collaboration: SharePoint, Teams, OneDrive, and Yammer working together for actual teamwork instead of email tag. Security: Built-in threat protection, data loss prevention, and encryption — without needing to bolt on third-party tools. Maintenance: Microsoft handles updates and patches, which frees IT staff for work that actually moves the business. Compliance: Features that help with HIPAA, GDPR, and the rest of the alphabet soup.

What types of Microsoft 365 migration does EdbMails support?

EdbMails covers all the standard Office 365 mailbox migration types. Cutover migration moves every source mailbox into the Office 365 tenant in a single pass — straightforward when the org is small enough to switch over at once. Staged migration breaks the work into phases, useful when you'd rather not move everyone at the same time. Hybrid migration ties on-premise Exchange and Office 365 together for organizations running both. IMAP migration is also on the menu — Gmail to Office 365 being one of the more common examples.

What are the best practices for Office 365 email migration?

The best practices guide for Office 365 mailbox migration covers all the key steps and recommendations to ensure a smooth and successful migration.

What are the migration challenges with Microsoft 365?

There are several common challenges with Office 365 mailbox migration including data integrity, downtime, user access continuity, and large mailbox handling. Detailed breakdown of these challenges is available in EdbMails' migration challenges guide.

Can I use EdbMails to migrate Microsoft 365 to On-Premise Exchange server?

Yes. EdbMails moves Office 365 mailbox data back to on-premise Exchange, with all server versions supported — Exchange 2010, 2013, 2016, and 2019. Step-by-step guidance for migrating from Office 365 to on-premise Exchange is available separately.

What are the steps to migrate Office 365 Public folder with EdbMails?

Public folder migration is straightforward with EdbMails — and there's no PowerShell scripting involved at any point. Step 1: Launch EdbMails and choose Office 365 migration. Step 2: Pick 'Connect to Public folder' as the migration operation. Step 3: Connect to the source Office 365 server and select the public folders. Step 4: Connect to the target Office 365 server and start the migration.

Can I migrate a Microsoft 365 Public folder to Shared mailbox with EdbMails?

Yes - Office 365 public folder to shared mailbox migration is one of the supported scenarios.

How to migrate a large Archive mailbox to Office 365 with EdbMails?

For migrating a large archive mailbox to Office 365: Step 1: Enable In-Place Archive in your Office 365 tenant. Step 2: Download and install EdbMails. Step 3: Connect to the source Office 365 server. Step 4: Pick the large archive mailbox you want to move. Step 5: Connect to the target Office 365 server. Step 6: Start the migration. Every piece of mailbox data — emails, contacts, calendars, tasks, attachments — comes across with full accuracy. No data loss, no corruption, nothing scrambled.

Which license do I need to buy to migrate Office 365 Mailboxes?

You'll need an Office 365 Migration license to move your mailboxes from Office 365.

Can I migrate only new emails using EdbMails without duplicates on the target server?

Yes. By default, the first run is a full migration. From the second run onward, incremental migration kicks in automatically, picking up only new or modified items — no duplicates land on the target. You can also filter by last migration date if you'd rather skip rescanning the whole mailbox each time.

Do I need to pay for Shared mailbox migration?

Yes — each shared mailbox uses up one license, same as a regular mailbox.

Is there a Free Trial version available to test Microsoft 365 migration features?

Yes — there's a Free Trial that opens up every Office 365 migration feature for testing. Up to 30 items per folder from every mailbox come across during the trial.

Is it possible to migrate specific data from source Office 365 to target Office 365?

Definitely. EdbMails handles selective Office 365 migration through filters that you can shape pretty granularly — message received date, sender address, recipients (CC and BCC included), subject line, attachment names, and read/unread status all work as filter criteria.

How do I choose the best Office 365 migration software?

Compare migration tools across capabilities like license type, concurrent mailbox migration, automatic throttling management, incremental migration, public folder licensing, and technical support. Tools that offer lifetime licenses, free upgrades, and 24/7 support typically deliver better long-term value than subscription-based options.

How does the licensing work?

The licensing model is per-mailbox: each migrated mailbox consumes one license, calculated against the source mailbox count. Nothing stops you from running multiple migration jobs in parallel across different machines, as long as you've got licenses left in the pool.

Do you have Office 365 Migration checklists?

Yes - Office 365 migration checklists are available to help you plan and execute your migration successfully.

How many licenses should I purchase for Public folder migration?

Public folder migration takes 20 mailbox licenses. Once those are allocated, you can migrate unlimited public folders from a domain — there's no per-folder cost beyond that.

Does EdbMails support migrating Shared mailboxes to Office 365?

Yes — shared mailbox migration to Office 365 tenants is fully supported. The full set of source items is covered: mailboxes, shared mailboxes, public folders, archive mailboxes, and more. EdbMails handles the shared-mailbox mapping automatically and brings across the contents — emails, attachments, contacts, calendars, tasks, and notes.

Is there any size limitation for Microsoft 365 mailbox migration?

There aren't any size limits on the EdbMails side. Microsoft does enforce its own restrictions, though — those are detailed in the EdbMails Knowledge Base article on Microsoft 365 mailbox size limitations.

Does EdbMails create the mailboxes automatically on the target O365 server?

Yes, EdbMails will automatically create the mailboxes for you on the target and allocate the licenses to be assigned.

Is it possible to map one source folder to the target folder of my choice on the server?

Yes, EdbMails allows customized folder mapping to route source folders to target folders of your choice.

How much time does it usually require to migrate Office 365 mailboxes?

The duration of Office 365 migration depends on a few moving parts. Detailed breakdown of Office 365 migration duration is available in EdbMails' tenant-to-tenant migration guide.

Does the software support all languages during migration?

Yes — EdbMails supports all languages during Office 365 migration.

Can I access the source and target mailbox during migration?

Yes — your mailbox data stays accessible the whole time the migration is running. No server downtime to plan around.

Can EdbMails remove deleted source items from the target Office 365 folders?

Yes — EdbMails can sync deletions from source to target. Tick the 'Remove deleted source items from target folders' option in the main migration window, then run a follow-up migration.

Can I migrate emails from Microsoft 365 to IMAP server using EdbMails?

Yes — Office 365 emails can move to any IMAP-enabled server. The supported list covers most of the popular ones: Outlook, Gmail, Zoho, Zimbra, IceWarp, cPanel, Plesk, GoDaddy, Rackspace, AWS WorkMail, Bluehost, and Dreamhost.

Does EdbMails support Office 365 to Hosted Exchange migration?

Yes — Office 365 to Hosted Exchange is supported. A common example is migrating from Office 365 to a Rackspace-hosted Exchange server.

Will I require a different license for Primary mailbox migration and Archive mailbox migration?

No, you only need one license if both the UPN (User Principal Name) are identical for the Primary and Archive mailboxes.

Does EdbMails manage mailbox mapping from source to target Microsoft 365 server automatically?

Yes, EdbMails automates the mailbox mapping between source and target tenants. For the case when there are hundreds or thousands of mailboxes to be migrated, manual mapping would be a terrible job and EdbMails saves a lot of time.

Does the software generate duplicates when running consecutive Microsoft 365 migrations?

No — incremental migration handles this. Subsequent runs only carry across new and modified items, which keep the target server clean of duplicates.

Does EdbMails handle mailbox mapping between source and target Microsoft 365 servers automatically?

EdbMails automates mailbox mapping between the source and target Tenants, which is useful for large-scale migrations, saving considerable time and effort compared to manual mapping.

Does EdbMails need scripting via PowerShell for Office 365 migration?

No. EdbMails Office 365 migration is an all-graphical-user-interface experience without need of using any PowerShell scripts, or any command-line instruments, or making any API calls. This is regardless of whether it is about migrating mailboxes across tenants, public folders or mailbox archives, hybrid configuration.

Parallel Office 365 Mailbox Migration

Office 365 Parallel Mailbox Migration

EdbMails Office 365 migration software supports concurrent mailbox migration, allowing multiple mailboxes to be processed in parallel rather than strictly one after another. This capability is useful for larger migration projects and planned migration windows, while actual completion time depends on mailbox characteristics, network bandwidth, source and target conditions, the migration machine, Microsoft 365 service availability, and applicable throttling.

EdbMails processes multiple mailboxes concurrently and provides configurable mailbox-level concurrency. Parallel processing can improve overall project throughput when resources and service conditions permit, but increasing concurrency does not remove Microsoft-controlled service limits. Built-in capabilities such as automatic mailbox mapping help administrators organize migration runs.

Why Parallel Migration is Crucial for Modern Organizations

Concurrent Mailbox Processing: Parallel migration processes multiple mailboxes at the same time. This can improve overall throughput compared with strictly sequential processing when network, system, source, target, and Microsoft 365 service conditions permit.
Microsoft 365 Throttling Still Applies: Concurrent processing can increase request volume. EdbMails can respond to throttling and retry according to its migration behavior, but parallel migration does not bypass Microsoft 365 service limits or resource-health controls.
Supports Planned Migration Windows: Processing several mailboxes concurrently can help administrators make better use of planned migration windows, although it does not guarantee a specific completion time.
Retry Handling: EdbMails includes retry behavior for migration interruptions and throttling scenarios. Administrators should still review migration results and reports to identify items or mailboxes that need attention.
Useful for Larger Migration Projects: Concurrent processing can be useful when many mailboxes need to be moved in a staged, consolidation, hybrid, or service-provider migration project.
Works with Repeat Migration Passes: Administrators can combine concurrent processing with incremental migration behavior for new or changed items on subsequent runs, while keeping parallel migration focused on mailbox-level concurrency.

Why Choose EdbMails for Parallel Mailbox Migration

Configurable Parallel Mailbox Processing
EdbMails can process up to 20 mailboxes concurrently. Administrators can tune mailbox-level concurrency according to available resources and observed migration conditions rather than relying on one universal default.
Throttling-aware migration behavior
Running more mailboxes at once can create more simultaneous requests. EdbMails provides automatic throttling management and retry behavior, while Microsoft 365 continues to control its own service limits and throttling.
Migration-window planning
Concurrent processing can help reduce elapsed project time when conditions permit. It should be planned alongside user communication, cutover activities, source/target readiness, and Microsoft 365 service behavior rather than treated as a zero-downtime guarantee.
Security remains part of each migration session
EdbMails uses supported authentication and secure connections for Office 365 migration. Parallel processing changes how migration work is distributed; it does not replace the page-specific controls described in secure Office 365 migration guidance.
Mailbox mapping for multi-mailbox runs
Automatic mailbox mapping can assist with source-to-target mailbox matching in multi-mailbox migration runs. Administrators should review mappings before migration.
Parallel runs can use incremental re-runs
A concurrent migration can be followed by an incremental migration pass so new or changed items can be processed according to EdbMails incremental behavior. Incremental migration remains a separate feature from mailbox-level concurrency.

What Determines Your Concurrency Ceiling

Useful concurrency depends on the complete migration environment rather than a fixed throughput formula. Microsoft 365 applies service and resource controls, so increasing the number of concurrent mailboxes does not create linear performance gains or remove Microsoft-controlled throttling.

Hardware, bandwidth, and service conditions set practical limits: Available CPU and memory on the migration machine, network bandwidth, mailbox size and item characteristics, source and target responsiveness, migration configuration, and Microsoft 365 service conditions can all affect useful concurrency. Administrators should monitor results and adjust the setting based on observed behavior.

Pause, resume, and repeat passes: EdbMails provides pause and resume capabilities and supports incremental repeat migration. Review the migration state and reports when resuming or rerunning a project rather than assuming every environment will behave identically.

Choosing the Right Concurrency Value

A concurrency value that is too low may leave available migration capacity unused, while a value that is too high can cause sessions to compete for local resources, bandwidth, or service capacity. The useful setting therefore depends on the environment and should be validated during the migration.

A practical approach is to start conservatively, monitor migration behavior, and adjust the mailbox-level concurrency setting within the supported range. EdbMails supports up to 20 concurrent mailboxes. Use observed throughput, resource usage, Microsoft 365 responses, and Office 365 migration filter settings when planning the amount of data processed in each run.

For very large projects, additional migration machines or separate project runs may be considered, but any improvement depends on network capacity, source and target conditions, licensing and application configuration, and Microsoft 365 service behavior. Do not assume proportional performance gains from adding machines or concurrent sessions.

When Parallel Migration Matters Most

Planned cutover windows: Concurrent processing can help administrators use a limited migration window more efficiently, but completion within a particular window depends on the environment and service conditions.
Large mailbox counts: Parallel processing is useful when several mailboxes need to be active at the same time. This capability is distinct from the broader Office 365 multiple mailbox migration scenario, which covers planning and execution across multiple mailboxes.
Tenant consolidation and mergers: Concurrent mailbox processing can be useful when a consolidation project includes many users and administrators need to stage or overlap mailbox transfers.
Service-provider and departmental projects: MSPs and internal teams can use concurrent processing to organize several mailbox transfers within planned project windows, subject to available resources and service conditions.

Parallel Migration vs Sequential Migration

Sequential migration processes mailboxes with little or no mailbox-level overlap. It can be appropriate for smaller or deliberately constrained runs and generally uses fewer concurrent migration resources.

Parallel migration processes multiple mailboxes concurrently up to the configured and supported limit. It can reduce overall elapsed time for larger projects when bandwidth, migration-machine resources, source and target responsiveness, and Microsoft 365 service conditions permit. It is not universally faster in every environment.

Administrators can tune concurrency as conditions change and then review Office 365 migration reports to evaluate migration results and determine whether the chosen setting is appropriate. A migration batch is an execution grouping concept; it is not automatically identical to parallel mailbox processing.

Related Office 365 Migration Scenarios

Parallel mailbox processing is one capability within broader Office 365 migration planning. For workload-specific procedures, see the Office 365 archive mailbox to Exchange guide, Office 365 public folder migration to Office 365 guide, Office 365 public folder to Exchange guide, and Office 365 migration to PST guide.

Setting Your Concurrency Value

Concurrent migration is available as part of the standard EdbMails Office 365 Migration workflow and does not require a separate setup process.

Download and install EdbMails, then open the application and log in or start a free trial.
Select the Office 365 Migration option and choose the migration type, such as Office 365 to Office 365, Office 365 to Live Exchange, or Office 365 to IMAP.
On the General tab, locate "Number of mailboxes to be migrated in parallel." Configure the mailbox-level concurrency value as appropriate for the project; EdbMails supports up to 20 concurrent mailboxes.
Optionally, adjust "Number of threads to be used for items migration within the mailboxes," set to 2 by default, to control how many parallel threads work within each individual mailbox during the migration.
Leave "Automatically resume the migration operation after a minute wait if server throttling occurs" at its default of 1 minute, or adjust it, to control how long EdbMails waits before resuming automatically if Office 365 throttling is encountered.
Click Next to continue connecting to the source and target servers, then proceed with the migration as usual.

For the complete step-by-step walkthrough of setting up and running an Office 365 migration with EdbMails, including how to connect to source and target servers and select mailboxes, see the step-by-step guide to concurrent mailbox migration.

Concurrent Office 365 Mailbox Migration

Boost Your Office 365 Migration with EdbMails Concurrent Mailbox Migration Solution