Best Email Client for Windows 11: Mailbird vs the New Outlook

Looking for Windows 11 Mail app alternatives? Microsoft ended support for the old Mail/Calendar/People apps and points Windows 11 users to the new Outlook for Windows. If you've been searching for an "email app Windows 11" replacement, this guide compares Outlook vs Mailbird so you can pick the best email client for Windows 11 based on how you actually work.

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Michael Bodekaer

Founder, Board Member

Oliver Jackson
Reviewer

Email Marketing Specialist

Jose Lopez
Tester

Head of Growth Engineering

Authored By Michael Bodekaer Founder, Board Member

Michael Bodekaer is a recognized authority in email management and productivity solutions, with over a decade of experience in simplifying communication workflows for individuals and businesses. As the co-founder of Mailbird and a TED speaker, Michael has been at the forefront of developing tools that revolutionize how users manage multiple email accounts. His insights have been featured in leading publications like TechRadar, and he is passionate about helping professionals adopt innovative solutions like unified inboxes, app integrations, and productivity-enhancing features to optimize their daily routines.

Reviewed By Oliver Jackson Email Marketing Specialist

Oliver is an accomplished email marketing specialist with more than a decade's worth of experience. His strategic and creative approach to email campaigns has driven significant growth and engagement for businesses across diverse industries. A thought leader in his field, Oliver is known for his insightful webinars and guest posts, where he shares his expert knowledge. His unique blend of skill, creativity, and understanding of audience dynamics make him a standout in the realm of email marketing.

Tested By Jose Lopez Head of Growth Engineering

José López is a Web Consultant & Developer with over 25 years of experience in the field. He is a full-stack developer who specializes in leading teams, managing operations, and developing complex cloud architectures. With expertise in areas such as Project Management, HTML, CSS, JS, PHP, and SQL, José enjoys mentoring fellow engineers and teaching them how to build and scale web applications.

Best Email Client for Windows 11: Mailbird vs the New Outlook
Best Email Client for Windows 11: Mailbird vs the New Outlook

Looking for Windows 11 Mail app alternatives? Microsoft ended support for the old Mail/Calendar/People apps and points Windows 11 users to the new Outlook for Windows. If you’ve been searching for an “email app Windows 11” replacement, this guide compares Outlook vs Mailbird so you can pick the best email client for Windows 11 based on how you actually work. 2

Key takeaways

  • Windows Mail, Calendar, and People ended support on December 31, 2024, so those apps can’t send/receive email or events anymore. 2
  • The new Outlook for Windows is positioned as the Windows 11 replacement (and the free experience can include ads without Microsoft 365). 2 4
  • Mailbird is built for multi-account workflows, including a Unified Inbox once you add more than one account (Mailbird Free supports 1 account; Premium is intended for unlimited accounts). 8 7
  • Microsoft notes the new Outlook supports IMAP/POP, but some classic Outlook capabilities are missing or limited (for example, COM add-ins aren’t supported and .pst support is only partial). 5
  • In work/school setups, restrictions and Exchange support can be deciding factors—check what your organization allows before you switch. 5 9
  • Offline expectations differ: Mailbird has a traditional desktop-client feel and supports backing up its local data; Outlook offline access exists but may require configuration. 10 6
  • Switching apps usually won’t delete mail for IMAP/Microsoft 365 accounts; POP can require exporting/backups first.

Quick pick (Windows 11 email software)

  • Choose Mailbird if you want a focused, customizable desktop workflow—especially if you manage 2+ inboxes and want a Unified Inbox (Mailbird Free supports 1 account; Premium is intended for unlimited accounts). 7 8
  • Choose Outlook for Windows (new) if you’re in Microsoft 365 work/school and want Microsoft’s built-in path on Windows 11 (the free experience can include ads without a Microsoft 365 subscription). 2 4
Table of contents

Mailbird vs Outlook for Windows (new): quick comparison

Top Windows 11 email software options compared
Decision criteria Mailbird Outlook for Windows (new)
Best fit A dedicated desktop inbox for managing multiple accounts with a cleaner daily flow. Microsoft’s Mail app replacement for Windows 11, especially in Microsoft 365 environments. 2
Multi-account “one place” workflow Built around a Unified Inbox concept (combine accounts into one view). 8 Multi-account capable, but strongest when your main account is Microsoft 365 + calendar/tasks. 4
Customization & integrations Emphasis on a customizable “workspace” feel with premium features like custom apps. 7 Emphasis on Microsoft 365 integration (mail, calendar, contacts, and to-dos in one ecosystem). 4
Work/school realities Great for standard IMAP/POP workflows and many Microsoft 365 setups; some org policies can block the protocols you need. 9 Strong support for Microsoft 365 accounts; on-prem Exchange can be limited in the new app. 5
Offline expectations Traditional desktop-client feel; you can back up local Mailbird data when needed. 10 Offline access exists, but feature coverage varies and you may need to enable it. 6
Cost model Freemium. Paid plans unlock the multi-account setup (Free is 1 account). 7 Included with Windows; free version can show inbox ads without a Microsoft 365 subscription. 2 4

Best fit

Mailbird
A dedicated desktop inbox for managing multiple accounts with a cleaner daily flow.
Outlook for Windows (new)
Microsoft’s Mail app replacement for Windows 11, especially in Microsoft 365 environments. 2

Multi-account “one place” workflow

Mailbird
Built around a Unified Inbox concept (combine accounts into one view). 8
Outlook for Windows (new)
Multi-account capable, but strongest when your main account is Microsoft 365 + calendar/tasks. 4

Customization & integrations

Mailbird
Emphasis on a customizable “workspace” feel with premium features like custom apps. 7
Outlook for Windows (new)
Emphasis on Microsoft 365 integration (mail, calendar, contacts, and to-dos in one ecosystem). 4

Work/school realities

Mailbird
Great for standard IMAP/POP workflows and many Microsoft 365 setups; some org policies can block the protocols you need. 9
Outlook for Windows (new)
Strong support for Microsoft 365 accounts; on-prem Exchange can be limited in the new app. 5

Offline expectations

Mailbird
Traditional desktop-client feel; you can back up local Mailbird data when needed. 10
Outlook for Windows (new)
Offline access exists, but feature coverage varies and you may need to enable it. 6

Cost model

Mailbird
Freemium. Paid plans unlock the multi-account setup (Free is 1 account). 7
Outlook for Windows (new)
Included with Windows; free version can show inbox ads without a Microsoft 365 subscription. 2 4

Quick details that trip people up:

  • Mailbird’s Unified Inbox appears after you add more than one account. 8
  • Mailbird Free supports 1 email account; Mailbird Premium supports unlimited accounts. 7
  • Microsoft’s comparison notes the new Outlook supports IMAP/POP, but some classic Outlook capabilities are missing or limited (for example, COM add-ins aren’t supported and .pst support is only partial). 5

Windows 11 Mail app alternatives: what changed (and why they matter)

Microsoft ended support for Windows Mail, Calendar, and People on December 31, 2024—meaning those apps can’t send/receive email or events anymore. Microsoft points users to the new Outlook for Windows and describes it as “built into Windows” and free to use. 2

The result: on Windows 11, Outlook will often be the default starting point, and your real decision is whether you accept it—or install a different email app (like Mailbird) and set that as your default mail experience. 2 3

What they are (one sentence each)

Mailbird: A Windows desktop email app that lets you manage multiple accounts in one place and optionally combine them into a Unified Inbox. 8

Outlook for Windows (new): Microsoft’s Outlook app for Windows 11 that supports common account types (including IMAP/POP) and is positioned as the replacement for Windows Mail & Calendar. 2 5

Key differences for Windows 11 users

1) Unified Inbox for multiple accounts: Mailbird

Pick Mailbird when your #1 goal is stopping the constant “which inbox am I in?” switching: Unified Inbox combines messages across connected accounts into a single view (and it only appears once you’ve added more than one account). If you’re planning a true multi-account setup, note that Mailbird Free is designed for one account per install—so this path usually means Mailbird Premium. 8 7

2) Microsoft 365 + meetings + scheduling: Outlook for Windows (new)

Pick Outlook for Windows when your primary account is a Microsoft 365 work/school mailbox and your “email” workflow is really email + calendar + contacts + tasks. Microsoft positions Outlook as a place to manage these together, and many organizations expect Outlook behavior because it sits at the center of scheduling and collaboration routines. 4

3) A customizable desktop “workspace”: Mailbird

Pick Mailbird if you want an inbox you can shape into a work surface (not just a place to read messages). Mailbird’s paid plans emphasize power-user conveniences like advanced search and “ custom apps ,” which is a different philosophy from “use Microsoft 365 apps around Outlook.” 7

4) Work/school restrictions and Exchange: Outlook is often safer, but check your setup

If your organization uses Microsoft 365 and locks down how mail clients connect, Outlook is usually the lowest-friction choice. Microsoft’s feature comparison also notes that on-prem Exchange support in the new Outlook is only “partially available” and supported via IMAP (with limitations based on protocol capabilities). 5

On the Mailbird side, Mailbird’s Microsoft OAuth 2.0 option doesn’t support on-prem Exchange server accounts. Mailbird also notes that connecting to Microsoft 365 via IMAP/POP can depend on org settings such as SMTP AUTH (which is disabled by default for new Microsoft 365 organizations). 9

5) Offline use: Mailbird for “desktop-first,” Outlook if you’re mostly online

If you travel, work on flaky Wi-Fi, or simply want predictable offline reading, Mailbird can be the more comfortable bet because it behaves like a traditional desktop client and you can back up its local data folder. Outlook can work offline too, but Microsoft frames it as something you enable and configure (for example, selecting how many days of email to save for offline access). 10 6

6) Ads vs paying for your client: depends what you hate more

Outlook for Windows has a free, ad-supported mode: Microsoft states that if you use a free email service (like Outlook.com, Hotmail, or Gmail) without a Microsoft 365 subscription, you’ll see ads in Outlook for Windows. Mailbird takes a more traditional freemium approach: start free, pay if you want the premium workflow (especially multi-account power use). 4 7

7) Windows 11 default-app convenience: Outlook for Windows (new)

If you want the path of least resistance on Windows 11, Outlook is hard to beat—because it’s increasingly “just there.” Microsoft’s admin guidance notes that Windows 11 builds later than 23H2 have the new Outlook app preinstalled for all users, and coverage notes the older Mail & Calendar apps aren’t installed by default on Windows 11 version 24H2. Mailbird can be set as your default mail app, but it’s an explicit choice you have to make. 3 1

Costs/effort/ownership trade-offs

Costs (US list pricing at time of writing)

  • Outlook for Windows: Positioned as included with Windows; Microsoft states the free version can show inbox ads unless you have a Microsoft 365 subscription. 2 4
  • Mailbird: Mailbird Free is $0 and includes 1 email account; Mailbird Premium is listed at $4 per user/month on a yearly plan; and Mailbird Premium “Pay Once” is listed at $99.75 as a one-time fee (both Premium options list unlimited accounts and 3 devices per license). 7

Effort

  • Outlook effort: Lowest install/setup effort on many Windows 11 PCs, because it’s often already present. Your biggest “effort cost” is adapting to how Microsoft wants Outlook to work. 3
  • Mailbird effort: Slightly higher initial setup (install + add accounts + set as default app), but you’re paying that effort once to get a workflow built for multiple inboxes.

Ownership

  • Outlook ownership: Great if you’re already paying for (and committed to) Microsoft 365; less great if you’re trying to avoid subscriptions or ads. 4
  • Mailbird ownership: You can choose an ongoing subscription or a one-time purchase style for Premium, depending on what fits your budget and how long you plan to keep the same setup. 7

Risks and dealbreakers

Mailbird is a bad choice if…

  • You need a guaranteed “works no matter what” experience in a heavily locked-down Microsoft 365 environment (where IMAP/SMTP might be restricted by policy).
  • Your email is on an on-prem Exchange server and you specifically need Microsoft OAuth 2.0 sign-in for that environment.
  • You want a free multi-account setup (Mailbird Free is designed for one account).

The specifics behind these dealbreakers are mostly about authentication and account rules (for example, Mailbird’s documentation notes OAuth 2.0 isn’t supported for on-prem Exchange server accounts, and it also notes that IMAP/POP can require org settings like SMTP AUTH). 9 7

Outlook for Windows (new) is a bad choice if…

  • You don’t want inbox ads and also don’t want a Microsoft 365 subscription to remove them.
  • You rely on classic Outlook-only capabilities (for example, COM add-ins), or you depend heavily on .pst workflows that the new Outlook only partially supports.
  • You’re on on-prem Exchange and need full Exchange behavior (the new Outlook’s on-prem Exchange experience can be limited).

Microsoft explicitly describes ads for free users without Microsoft 365, and its feature comparison documents several differences between classic Outlook and the new Outlook (including COM add-ins not being supported and .pst support being partial). 4 5

Switching path: if you chose wrong, how to change direction with minimal loss

If you started with Outlook and want to move to Mailbird

  1. Install Mailbird and add your accounts.
  2. For Microsoft 365 accounts: use the Microsoft OAuth 2.0 sign-in option if prompted. 9
  3. Enable Unified Inbox once you have multiple accounts connected. 8
  4. Set Mailbird as your default mail app in Windows 11 (so mailto: links open the right client).

Unified Inbox appears after you add more than one account, and Mailbird’s documentation covers Microsoft 365 OAuth 2.0 handling and related edge cases. 8 9

If you started with Mailbird and want to move to Outlook

  1. Add the same accounts to Outlook for Windows (IMAP/POP accounts are supported). 5
  2. If you used POP anywhere: back up and export first, because POP mail is often stored locally in your client.
  3. Keep both apps for a week so you can verify your folders, sent mail, signatures, and notifications behave the way you expect.

Mailbird provides guidance for backing up its local data folder and offers an Export Tool that can export POP3/IMAP data to .eml files or upload it to an IMAP server (helpful when you’re trying to move historical mail). 10 11

If you’re coming from the old Windows 11 Mail app

  1. Assume you’re migrating: Microsoft ended support for the old Mail/Calendar/People apps. 2
  2. Decide your direction: Outlook for Windows if you want Microsoft’s default path, or Mailbird if you want a dedicated multi-account desktop client.
  3. Export anything local before you wipe/reset a PC (Microsoft notes local Mail/Calendar/People items remain exportable). 2

Decision tree (force a choice)

  • If your primary inbox is a Microsoft 365 work/school account and your org expects Outlook behavior, then choose Outlook for Windows .
  • If you manage 2+ accounts daily and want to treat them like one inbox, then choose Mailbird (Premium if you need more than one account). 7
  • If you want the simplest “already on Windows 11” starting point and you’re fine with Microsoft’s direction, then choose Outlook for Windows . 3
  • If you want a customizable desktop workflow and prefer paying for features instead of living with inbox ads, then choose Mailbird . 4 7
  • If you’ve tried the new Outlook and it still feels like a downgrade from what you want, then choose Mailbird and make it your default app.

Frequently Asked Questions

Is the Windows 11 Mail app still supported?

No. Microsoft ended support for Windows Mail, Calendar, and People on December 31, 2024, and those apps can’t send/receive email or events anymore. 2

What replaced the Windows 11 Mail app?

Microsoft points Windows 11 users to the new Outlook for Windows as “the future of Mail, Calendar, and People on Windows 11.” 2

Is Outlook for Windows free on Windows 11?

Outlook for Windows is positioned as built into Windows and free to use. If you don’t have a Microsoft 365 subscription, Microsoft says you may see ads. 2 4

Does Outlook for Windows support Gmail, Yahoo, and IMAP/POP accounts?

Yes. Microsoft’s feature comparison states that the new Outlook supports common providers and also standard IMAP and POP account types. 5

Can Mailbird manage multiple email accounts on Windows 11?

Yes. Mailbird can handle multiple accounts, but Mailbird Free is designed for one account; Premium plans are intended for unlimited-account setups. 7

Does Mailbird have a unified inbox?

Yes. When you add more than one account, you can use Unified Inbox to see messages from those accounts in one combined view. 8

Does Mailbird support Microsoft 365 OAuth 2.0 (modern authentication)?

Yes. Mailbird supports Microsoft Office 365 OAuth 2.0 modern authentication, with documented limitations (for example, it doesn’t support on-prem Exchange server accounts). 9

How do I set Mailbird as the default email app in Windows 11?

Open Windows 11 Settings → Apps → Default apps, search for Mailbird, and set it as the default for mail-related file types and the MAILTO protocol.

Will switching email apps delete my emails?

Usually not if your accounts are IMAP or Microsoft 365, because your messages live on the server and the new app simply syncs them. POP accounts are different—back up and export first if you have important local-only mail.

Can I run Mailbird and Outlook for Windows side by side?

Yes. Many people keep both installed during a transition—use one as your default app and keep the other as a fallback until you’re confident everything is syncing and sending correctly.

Sources

  1. Windows Central — Notes that Mail & Calendar aren’t installed by default after Windows 11, version 24H2 (Oct 22, 2025)
  2. Microsoft Support — Outlook for Windows: The Future of Mail, Calendar, and People on Windows 11 (Mail/Calendar support ended Dec 31, 2024; Outlook built into Windows)
  3. Microsoft Learn — Control Installing and Using New Outlook (preinstall behavior on Windows 11 builds later than 23H2)
  4. Microsoft 365 — Outlook for Windows page (ads policy for free users; subscription removes ads)
  5. Microsoft Support — Feature comparison between new Outlook and classic Outlook (account support, add-ins, .pst status, offline status)
  6. Microsoft Support — Work offline in Outlook (offline access behavior in the new Outlook for Windows)
  7. Mailbird — Pricing page (Free vs Premium, Pay Once option, devices per license): https://hub.getmailbird.com/pricing
  8. Mailbird Support — Unified Inbox (what it is, when it appears, how it works): https://support.getmailbird.com/hc/en-us/articles/220108147-Unified-Inbox
  9. Mailbird Support — Microsoft 365 OAuth 2.0 (modern authentication) support (limitations and setup notes): https://support.getmailbird.com/hc/en-us/articles/360052453913-Microsoft-Office-365-OAuth-2-0-modern-authentication-support
  10. Mailbird Support — How to back up your email data (Windows data folder backup steps): https://support.getmailbird.com/hc/en-us/articles/115003544187-How-to-backup-your-email-data
  11. Mailbird Support — How to use Mailbird’s Export Tool (.eml export or upload to an IMAP server): https://support.getmailbird.com/hc/en-us/articles/115013591887-How-to-Use-Mailbird-s-Export-Tool
  12. Mailbird Support — Promotions and volume discounts note (pricing and promos can vary): https://support.getmailbird.com/hc/en-us/articles/360038912334-Does-Mailbird-Offer-Discounts-for-Purchases-of-Multiple-Licenses