OpenText GroupWise vs Microsoft 365: an honest comparison for UK SMEs weighing a move

GroupWise and Microsoft 365 are both mature, capable email and calendaring platforms that have been in market for decades. The question for most UK SMEs is no longer "is the cloud better in theory" — it is whether the operational, financial and security trade-offs of staying on-premise still make sense for their particular business. There is no universal answer; there is a small number of patterns where each platform is the right choice. This article is meant to make those patterns obvious.

What you are actually comparing

Both platforms deliver the four things every business depends on: reliable email, shared calendars, address books, and shared folders. GroupWise does it with a Post Office Agent on your own server, GWIA for SMTP, Web Access for browser clients and optional native clients. Microsoft 365 does the same four things but in the cloud, with Exchange Online, Outlook, the Office web apps and OneDrive. Power and feature parity is much closer than it used to be: GroupWise calendaring is solid, and Outlook plus Exchange Online still represents the gold standard that GroupWise is compared against.

Cost and licensing

GroupWise licensing is a one-off or annual subscription per concurrent user, with no per-mailbox cloud component. Beyond the licence you pay for the server you run it on, the storage it consumes, the backup infrastructure and the human time to keep it healthy. Microsoft 365 is the opposite: a monthly per-user licence that bundles Exchange, Teams, SharePoint, OneDrive, the Office apps and an increasingly large security stack. For an SME under fifty users GroupWise is usually cheaper; for an SME between one and three hundred users the comparison flips once you add the cost of running the on-premise estate properly. Above three hundred users Microsoft 365 wins on cost almost every time we model it.

Security and compliance

• Identity: Microsoft 365 is anchored on Entra ID with conditional access, MFA enforcement, identity protection and risk-based policies. GroupWise relies on the identity store you put in front of it, most commonly eDirectory, with whatever SSO bridge you have built.
• Endpoint: Microsoft 365 Business Premium and E3/E5 ship with Defender for Business or Defender for Endpoint, Intune and the full Microsoft XDR loop. GroupWise is shielded only by whatever endpoint protection runs on the clients connecting to it.
• Compliance: DLP, sensitivity labels, eDiscovery, customer key encryption and audit pipelines are first-class on Microsoft 365. The same capabilities on GroupWise require third-party tooling.
• Insurance: most cyber-insurance questionnaires in 2026 assume cloud email with MFA and conditional access. Running GroupWise is not a deal-breaker, but it is increasingly a question you have to answer.
• Data residency: GroupWise keeps data in your datacentre by construction. Microsoft 365 offers UK and EU data residency at the licence level. For some SMEs the on-premise story still wins on this one point alone.

Mobile, web and modern UX

Outlook on mobile is the most polished email client on any platform, and the web app is the de facto standard against which everything else is judged. GroupWise Web Access is functional and has improved over the years, but it is nowhere near Outlook in fit and finish. Third-party GroupWise mobile clients exist and are competent, but they are not part of a unified Microsoft-style productivity surface. If your team works on phones and tablets for a significant part of the day, that gap matters.

Ecosystem and integrations

Microsoft 365 is the centre of gravity for the modern SME productivity stack: Teams for chat and meetings, SharePoint for intranets and document management, Power Automate for workflow, Power Apps for line-of-business tools, Graph API for custom integrations. GroupWise integrates with its own set of tools and a smaller ecosystem of third-party connectors. If your roadmap includes anything built on Microsoft Teams, Copilot, Graph-based integration with line-of-business systems, or modern identity governance, GroupWise will always be the limiting factor rather than the enabling one.

The honest case for staying on GroupWise

There genuinely is a case. If you are a small organisation with stable headcount, you already have the skills to run Linux, OES and GroupWise well, your data residency requirements genuinely demand on-premise, your internet connectivity is patchy enough that cloud email would be a real risk, and you have no appetite for the AI productivity features that Microsoft 365 is now bundling — GroupWise remains a sensible answer. The mistake is to stay for the wrong reason: because the migration feels expensive or scary, not because staying is genuinely the better choice. That is a decision that ages badly.

We help SMEs across Hertfordshire, Bedfordshire and London design Microsoft 365 migrations that do not break the business, and we help the smaller number who choose to stay build a sensible lifecycle plan for GroupWise. If you are weighing the move, get in touch for a one-hour scoping conversation.