Technology · head to head
Microsoft Outlook vs Redis
Microsoft Outlook
Technology
Microsoft's email and calendar client, in the middle of a transition from the classic Windows application to a web-based replacement.
- From
- Free
- Rated
- -
The short version
- Each has a real cost: Microsoft Outlook microsoft is replacing the classic Win32 client with the new web-based Outlook, and the new one runs only web add-ins, not COM add-ins, so any line-of-business integration for CRM, dictation, document management or telephony must be rewritten or the desktop stays on classic until its support window closes.; Redis licensing changed from BSD to AGPL in 2025, impacting open-source usage
- They diverge on capability: Microsoft Outlook covers Exchange calendar integration, Redis covers In-memory data store.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which Microsoft Outlook and Redis actually diverge.
| Attribute | Microsoft Outlook | Redis |
|---|---|---|
| Pricing model | freemium | Unknown |
| Platforms | Web | Linux, macOS, Windows |
| Founded | Unknown | 2009 |
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Technology).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in Microsoft Outlook
- Exchange calendar integration
- Delegate access
- Shared mailboxes
- Rules and Quick Steps
- Retention, hold and eDiscovery
- Sensitivity labels and encryption
- Add-in platform
- Offline cached mode
Only in Redis
- In-memory data store
- Data structures
- Pub/Sub messaging
- Lua scripting
- Transactions
- Persistence options
- Replication
- Clustering
What people use each for
The jobs each tool is most often brought in to do.
Microsoft Outlook
- Organisations on Exchange Online or Exchange Server where free/busy scheduling and room booking across everyone is a daily requirementnot Redis
- Executive assistants managing someone else's calendar and mailbox through delegate access, which no IMAP client supports properlynot Redis
- Regulated environments that need retention policies, legal hold and eDiscovery applied to mail centrally rather than per usernot Redis
- Teams handling shared inboxes such as support or accounts, where permissions and tracking matter more than the mail client itselfnot Redis
Redis
- Cachingnot Microsoft Outlook
- Session managementnot Microsoft Outlook
- Real-time analyticsnot Microsoft Outlook
- Message queuingnot Microsoft Outlook
- Leaderboardsnot Microsoft Outlook
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Microsoft Outlook
- Microsoft is replacing the classic Win32 client with the new web-based Outlook, and the new one runs only web add-ins, not COM add-ins, so any line-of-business integration for CRM, dictation, document management or telephony must be rewritten or the desktop stays on classic until its support window closes.
- The new client's handling of non-Microsoft accounts synchronises mail through Microsoft's cloud rather than connecting from the machine to the provider, which several organisations' data residency and handling policies do not allow, and it is not an optional behaviour.
- PST and OST files are a single-file, corruptible and effectively unshareable store, and the new client's reduced PST support means years of personal archives sitting in those files need an explicit migration plan rather than carrying forward.
- Large mailboxes turn software problems into administration ones: search index rebuilds, OST files of tens of gigabytes and the mailbox quotas of whichever plan was bought, and the usual fix is archiving policy rather than anything a user can do.
- Against IMAP or Gmail you lose most of what justifies it, including free/busy lookup, room booking, delegate access, and retention and compliance policies, because those are Exchange server features rather than client features.
- The five or six products sharing the Outlook name have materially different feature sets, so internal documentation, training and support procedures must be written per platform and a user moving between desktop, web and mobile finds the same task done differently in each.
Redis
- Licensing changed from BSD to AGPL in 2025, impacting open-source usage
- All data must fit in memory, limiting scalability to available RAM
- No built-in support for multi-tenancy
- Limited transaction support compared to traditional databases
Pricing, plan by plan
Microsoft Outlook
Free- Outlook (Free)Free
- 15 GB mailbox storage
- 5 GB cloud storage
- Web and mobile Office app access
- Microsoft 365 Basic$1.99/month
- 100 GB mailbox storage
- 100 GB cloud storage
- Ad-free experience
- Microsoft 365 Personal$9.99/month
- 1 TB cloud storage
- Desktop Office apps (Word, Excel, PowerPoint, Outlook, OneNote)
- Copilot with high usage limits
- Microsoft 365 Family$12.99/month
- 1-6 users
- Up to 6 TB total cloud storage (1 TB per person)
- Same apps and features as Personal
Redis
FreeNo published plan breakdown. See the Redis review.
Which should you pick?
Choose Microsoft Outlook if
- You need exchange calendar integration.
- You want to start without paying.
- You also want delegate access.
Choose Redis if
- You need in-memory data store.
- You want to start without paying.
- You work on Linux, macOS, Windows.
- You also want data structures.
Questions people ask
- Is Microsoft Outlook or Redis better?
- Neither clearly leads. Microsoft Outlook starts at Free and Redis at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Microsoft Outlook or Redis?
- Microsoft Outlook starts at Free and Redis at Free.
- Does Microsoft Outlook or Redis run on more platforms?
- Microsoft Outlook runs on Web. Redis runs on Linux, macOS, Windows.
- Can I use Microsoft Outlook for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Microsoft Outlook best used for?
- Microsoft Outlook is most often used for organisations on exchange online or exchange server where free/busy scheduling and room booking across everyone is a daily requirement, executive assistants managing someone else's calendar and mailbox through delegate access, which no imap client supports properly, regulated environments that need retention policies, legal hold and ediscovery applied to mail centrally rather than per user, teams handling shared inboxes such as support or accounts, where permissions and tracking matter more than the mail client itself. Of those, organisations on exchange online or exchange server where free/busy scheduling and room booking across everyone is a daily requirement and executive assistants managing someone else's calendar and mailbox through delegate access, which no imap client supports properly are not what Redis is typically brought in for.
- What can Microsoft Outlook do that Redis cannot?
- Microsoft Outlook covers Exchange calendar integration, Delegate access, Shared mailboxes, Rules and Quick Steps. Redis covers In-memory data store, Data structures, Pub/Sub messaging, Lua scripting.
Answered from the vendors’ own pages
Microsoft Outlook: What is the difference between classic Outlook and the new Outlook for Windows?
Classic is the long-standing Win32 application shipped with Microsoft 365 and Office LTSC. The new Outlook is a web-based client that replaced Windows Mail and Calendar. The most consequential difference is add-ins: the new client supports only web add-ins, not COM add-ins.
Redis: Is Redis open source?
Redis was open source under the BSD license since its inception in 2009 and has remained open source. However, in 2024-2025, Redis Labs changed licensing to source-available and AGPL, prompting the creation of Valkey, a BSD-licensed open-source fork.
SourceMicrosoft Outlook: How long will classic Outlook be supported?
Microsoft has stated support through at least 2029. That is a planning window rather than a reprieve, and organisations with COM add-in dependencies should be scoping the replacement work now.
Redis: What is Redis used for?
Redis is an in-memory data structure store used primarily as a cache, database, and message broker. It provides high-speed data access for real-time applications, sessions, leaderboards, real-time analytics, and other use cases requiring fast data retrieval.
SourceMicrosoft Outlook: Can I use Outlook with Gmail or another IMAP provider?
Yes, but with reduced capability. You lose free/busy lookup, room booking, delegate access and server-side compliance policies, because those come from Exchange rather than from the client.
Microsoft Outlook: Is Outlook free?
Outlook on the web and the mobile apps are free with a Microsoft account, and the new Outlook for Windows is included with Windows 11. The classic desktop application requires a Microsoft 365 subscription or an Office perpetual licence.
Microsoft Outlook: Will my COM add-ins work in the new Outlook?
No. The new client supports only the cross-platform web add-in model. Vendors must publish a web add-in, and where they have not, the choice is to stay on classic Outlook or replace the integration.
Related pages
More on Microsoft Outlook
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