We deploy, migrate and operate your business email on on-premises Exchange Server, on Exchange Online (Microsoft 365), or on a hybrid architecture that uses both.
Our Exchange email service covers both products: Exchange Server running on your premises and Exchange Online, part of Microsoft 365. New deployments, version upgrades, cloud migration, hybrid setups, email security, backup and day-to-day operations are handled in a single project plan.
Both products deliver the same Outlook experience; the difference is who owns the infrastructure, who applies updates and how licensing is paid. The table below is a starting point for the first decision.
| Criterion | Exchange Server (on-premises) | Exchange Online | Hybrid |
|---|---|---|---|
| Infrastructure | Your own servers or virtualization platform | Microsoft data centers | Both |
| Updates and patching | CUs and security updates are your responsibility | Managed by Microsoft | Your responsibility for on-premises servers |
| Data location | Full control in your own data center | Microsoft data centers in the tenant region | Chosen per mailbox |
| Licensing | Exchange Server SE server and CAL subscription | Per-user subscription (Plan 1/Plan 2 or Microsoft 365 plans) | A combination of both |
| Mailbox size | Depends on your storage capacity | Plan 1: 50 GB, Plan 2: 100 GB plus archive | Depends on where the mailbox lives |
| High availability | Designed with a Database Availability Group (DAG) | Covered by Microsoft's service level commitment | Each side in its own model |
| Best fit | Organizations with data residency or compliance requirements | Organizations that want to stop running mail servers | Organizations migrating in stages |
With on-premises Exchange, mailbox data stays in your infrastructure, and so does responsibility for servers, storage, updates and security. Deployment and operations cover:
Microsoft ended support for Exchange Server 2016 and 2019 on October 14, 2025. Standard security updates are no longer released for these versions. The successor for on-premises Exchange is Exchange Server Subscription Edition (SE), generally available since July 1, 2025.
In Exchange Online, servers, updates and hardware are Microsoft's responsibility; identity, licensing, security policies and user management remain on your side.
The migration method is chosen based on mailbox count, the current Exchange version and how long the migration will run:
In every method, DNS TTL values are lowered in advance, pilot users test first and the MX record is switched last. In environments synchronized with on-premises Active Directory, Exchange management tools are still needed for recipient management after all mailboxes have moved. Old servers are properly decommissioned before they are shut down.
Major mailbox providers require SPF, DKIM and DMARC alignment for bulk senders. A poorly configured domain stays open to spoofing and increases the chance that your own mail lands in spam.
In Exchange Online, Microsoft is responsible for service continuity; protection against deletion, user error or ransomware is your responsibility. Retention policies do not replace an independent backup. On premises, a DAG is not a backup method either.
Organizations whose Exchange 2016 or 2019 servers are out of support, organizations moving email to Microsoft 365, organizations that must keep on-premises Exchange for data residency, and businesses that want one corporate email platform across several locations.
Before migrating, we list everything that depends on email: printers that scan to email, business applications using SMTP, integrations using EWS, shared mailboxes and mobile devices. What breaks during a migration is usually not the mailbox itself but one of these forgotten dependencies.
A hypothetical organization runs Exchange 2016 at two locations and the servers are out of support. Most mailboxes move to Exchange Online through a hybrid migration; Exchange Server SE is deployed for a few mailboxes that must stay on premises for compliance. The MX record is switched after pilot tests and the old servers are properly decommissioned.
The decision depends on data residency and compliance requirements, existing hardware and operations staff, budget model (capital spend or subscription) and the applications that depend on email. Exchange Online suits organizations that do not want to run infrastructure, Exchange Server SE suits cases where data must stay on premises, and a hybrid setup suits staged migrations or keeping some mailboxes on premises.
Microsoft support for Exchange Server 2016 and 2019 ended on October 14, 2025, and standard security updates are no longer released for these versions. Because Exchange is an internet-facing service, an unpatched server is a serious risk. An upgrade to Exchange Server SE or a move to Exchange Online should be planned.
Exchange Server SE RTM is code-equivalent to Exchange 2019 CU15 and can be installed like a cumulative update on servers running Exchange 2019 CU14 or CU15, with no Active Directory schema changes. Exchange 2016 environments require a side-by-side migration, moving mailboxes to new servers.
Mailboxes are copied with a hybrid or cutover migration, DNS TTL values are lowered in advance and the MX record is switched last. Because the migration runs in a planned window and is tested with pilot users first, user impact and downtime risk are kept to a minimum.
Plan 1 provides a 50 GB mailbox per user. Plan 2 provides a 100 GB mailbox, auto-expanding archiving and advanced compliance features such as data loss prevention (DLP). Exchange Online is also included in Microsoft 365 Business and Enterprise plans; current plan features are confirmed against Microsoft sources at the proposal stage.
Yes, it is recommended. Microsoft 365 follows a shared responsibility model; retention policies and the deleted items folder do not replace an independent backup. A solution such as Veeam Backup for Microsoft 365 backs mailboxes up to a separate location, and restores are tested.
Yes. The domain is verified and the MX, Autodiscover, SPF, DKIM and DMARC records are updated for the new setup. Users keep their email addresses.
Applications that use Exchange Web Services (EWS), such as CRM, archiving, backup and older integrations, are being blocked in Exchange Online in phases starting October 1, 2026, with full retirement on April 1, 2027. These applications need to move to Microsoft Graph. EWS on on-premises Exchange Server is not affected.
