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Thunderbird, eM Client, and Mailbird are three Windows email apps worth comparing if you don’t want to use New Outlook. None can be called the best choice for every reader based on the available evidence: your account provider, offline and archive needs, Outlook features, calendar and contact requirements, and budget determine which one fits. Treat this as a shortlist, not a tested ranking, and confirm specific requirements in the app’s current documentation before switching.
Why check your Outlook workflow before switching?
New Outlook does not support every capability found in classic Outlook. Microsoft’s feature comparison, updated September 23, 2026, marks New Outlook’s offline support and PST support as partially available, and COM add-ins and VBA macros as unsupported. The matrix also marks network-share file access and the Outlook Object Model as unsupported. Microsoft describes New Outlook as inspired by Outlook on the web and built with WebView2 in a Native Windows Integration Component; its documentation says COM add-ins are not supported.
These are findings about Microsoft’s Outlook versions, not evidence that any third-party app replaces those capabilities. Microsoft’s matrix defines statuses including available, partially available, unsupported, under investigation, and upcoming, and notes that it does not list every capability. Check the current Outlook feature comparison before making a decision because statuses and dates can change. Microsoft’s description of New Outlook is that it is “reimagined to be more agile, deliver faster feature deployment and availability, and provide a consistent experience in Windows.”
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The official product pages identify these as desktop email-client candidates. They do not, by themselves, establish a complete comparison of current features, pricing, account compatibility, or Outlook workflow support.
#1 Best Overall
- THREAT DETECTION – Stay one step ahead. Suspicious links, risky sites, viruses, and scams, caught automatically before they reach you.
- PERSONAL INFO PROTECTION – Keep your personal info safer. Identity monitoring watches for your exposed info and tells you what to do about it.
- SECURE CONNECTIONS – Just a few easy clicks, and we'll automatically protect your info on public Wi‑Fi, every time you connect.
- GUIDED ACTION – Know what matters and what to do next. Clear alerts and simple guidance make it easy to take action.
- MORE THAN ANTIVIRUS – Scam protection, identity monitoring, VPN, web protection, and antivirus work together to protect you, all in one place.
| App | What is established | What to confirm for your setup |
|---|---|---|
| Thunderbird | Mozilla presents Thunderbird as a desktop email app. See Thunderbird’s desktop page. | Windows requirements, support for your provider and account type, offline behavior, calendar and contact needs, archive handling, and current costs or limits. |
| eM Client | Its official page identifies it as an email client for Windows and Mac. See eM Client. | Current plan limits, account compatibility, offline and archive behavior, calendar and contact functions, and license or subscription terms. |
| Mailbird | Its official page identifies it as an email client for Windows and Mac. See Mailbird. | Current plan limits, account compatibility, offline and archive behavior, calendar and contact functions, and license or subscription terms. |
This is a relevance-based shortlist, not a claim that these apps are superior to New Outlook or that any is a drop-in replacement. No hands-on testing or full vendor-by-vendor feature and price comparison is established here.
Quick Recap
Rank #4
- THREAT DETECTION – Stay one step ahead. Suspicious links, risky sites, viruses, and scams, caught automatically before they reach you.
- PERSONAL INFO PROTECTION – Keep your personal info safer. Identity monitoring watches for your exposed info and tells you what to do about it.
- SECURE CONNECTIONS – Just a few easy clicks, and we'll automatically protect your info on public Wi‑Fi, every time you connect.
- GUIDED ACTION – Know what matters and what to do next. Clear alerts and simple guidance make it easy to take action.
- MORE THAN ANTIVIRUS – Scam protection, identity monitoring, VPN, web protection, and antivirus work together to protect you, all in one place.
Rank #2
- THREAT DETECTION – Stay one step ahead. Suspicious links, risky sites, viruses, and scams, caught automatically before they reach you.
- PERSONAL INFO PROTECTION – Keep your personal info safer. Identity monitoring watches for your exposed info and tells you what to do about it.
- SECURE CONNECTIONS – Just a few easy clicks, and we'll automatically protect your info on public Wi‑Fi, every time you connect.
- GUIDED ACTION – Know what matters and what to do next. Clear alerts and simple guidance make it easy to take action.
- MORE THAN ANTIVIRUS – Scam protection, identity monitoring, VPN, web protection, and antivirus work together to protect you, all in one place.
How to choose the right app for your needs
- Work or personal account: Verify that the app supports your provider and account type, and that it meets any requirements set by your organization.
- Offline use: Find out exactly which mail and other data remain accessible without an internet connection. “Offline support” can mean different things; check the app’s documentation for your intended use.
- Existing archive: If you have a PST or another archive format, confirm whether the app can open or import it and which data is preserved. Do not assume support from the fact that the app handles email.
- Outlook-dependent work: List the add-ins, rules, macros, delegates, shared mailboxes, and other features you actually use. Check each one against current vendor documentation before moving essential work.
- Calendar and contacts: Confirm that the functions you rely on are included and that synchronization works with your accounts and devices.
- Cost: Check the vendor’s current pricing and licensing terms, including any free-tier limits, before committing. Prices and plan features are not established here.
A practical way to make the switch decision
- Write down what you use in classic Outlook. Include account types, offline tasks, archive files, add-ins or macros, shared mailboxes or delegation, and calendar or contact workflows.
- Check Microsoft’s current feature matrix. Use the dated status information to identify where New Outlook differs from classic Outlook, then verify any capability that is essential to you.
- Compare the same requirements against each candidate. Consult the official pages for Thunderbird, eM Client, and Mailbird. If a requirement is not clearly documented, ask the vendor rather than assuming it is supported.
- Confirm cost and limits directly with the vendor. Review current Windows requirements, plan terms, account support, offline behavior, and import or export details before changing your daily setup.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
