Exchange Server Alternative
Email, calendars and contacts with European mail servers, on your own servers instead of Exchange by subscription or in the cloud.
Microsoft ended support for Exchange Server 2016 and 2019 on October 14, 2025. The successor, Exchange Server Subscription Edition, is only supported with an active subscription, and Microsoft’s alternative is moving to Exchange Online.
European mail servers such as Open-Xchange, grommunio and mailcow provide email, calendars and contacts on your own servers. grommunio connects Outlook just like Exchange.
BARNICOM plans the switch, migrates mailboxes and runs the new mail server with spam protection, backup and delivery monitoring.
Why companies are switching now
Support has ended
Exchange Server 2016 and 2019 have received no security updates since October 14, 2025 (Microsoft). A mail server without updates is a serious risk.
Successor by subscription only
The successor, Exchange Server Subscription Edition, is only supported with an active subscription. Microsoft’s alternative is moving to the cloud.
Access under US law
The US CLOUD Act requires US providers to hand over data to US authorities on request, even when it is stored in Europe (CLOUD Act explained).
What replaces what
Exchange functions and European mail servers that cover them. Which solution fits is something we work out together.
| Area | Exchange Server SE | Exchange Online | European alternatives |
|---|---|---|---|
| Mailboxes, calendars, contacts | Exchange Server | Exchange Online | Open-Xchange, grommunio or mailcowGermany, Austria |
| Outlook on the PC | MAPI | MAPI | grommunio with native Outlook support, otherwise IMAP or ActiveSyncAustria |
| Smartphones | ActiveSync | ActiveSync | ActiveSync with grommunio and mailcowAustria, Germany |
| Spam and virus protection | Exchange Online Protection | Defender for Office 365 | rspamd and ClamAVOpen source |
| Archiving | Archive mailboxes | Exchange Online Archiving | MailStore or pilerGermany, open source |
Origin refers to the vendor’s headquarters.
How the switch works
-
Assessment
How many mailboxes, which clients, which links to business software? The result is a plan with effort and timeline.
-
Test run
A test group’s mailboxes run on the new server, and Outlook, smartphones and delivery are checked.
-
Migration
Mailboxes, calendars and contacts are transferred, and mail delivery switches on a fixed date.
-
Operations
We take care of updates, monitoring, backup and support, with a service level agreement on request.
When the alternative is not a fit
Switching does not make sense in every case. We point out limitations beforehand, for example with:
- business software that strictly requires Exchange interfaces such as EWS
- heavy use of Outlook add-ins
- mixed environments meant to stay closely tied to Microsoft 365
Frequently asked questions
Does our Exchange 2019 keep running after end of support?
Yes, the server keeps running but receives no more security updates. Newly discovered vulnerabilities stay open, which is risky for a mail server reachable from the internet.
Can we keep using Outlook?
Yes. With grommunio, Outlook connects as it does to Exchange, with mail, calendar and contacts. With the other solutions, Outlook works via IMAP or ActiveSync.
What is Open-Xchange?
Open-Xchange is email and groupware software from Germany. The German state of Schleswig-Holstein moved its mailboxes from Exchange to it in 2025, and it is part of openDesk.
Will emails be lost during migration?
No. Mailboxes are copied completely while the old server keeps running. Delivery only switches after everything has been checked.
What does the switch cost?
It depends on the number of mailboxes, data volume and archiving. You receive a proposal after the assessment.
More alternatives for workplace and collaboration
Replace your Exchange Server
We review your mail environment and tell you which mail server fits.