Microsoft Outlook alternatives: 11 email client tools compared
People look for an Outlook alternative for three different reasons: the free version shows ads in the inbox, the new Windows app drops add-ins and macros that the classic one ran, or a small office pays for a Microsoft 365 plan mainly to read mail. They move to a free open-source client, to a one-off licence, or to a client built around one mail provider.
Short answer: The first three alternatives to Microsoft Outlook in our email client software ranking are Mozilla Thunderbird, eM Client and Mailbird. Places 1 to 3 go to challengers, vendors outside the best-known brands in a category, wherever the category has them; the established names follow from place 4 in their ranked order. Choose Mozilla Thunderbird if you want a free desktop client with no ads and no subscription behind it. All 11 alternatives below are ranked products from Best Email Client Software in 2026, and each says where it differs from Microsoft Outlook.
Vendors can pay for visibility on this site; it never changes what we say
about a product. How that works.
Pricing: Free version with ads; a Microsoft 365 subscription removes them (plan prices on Microsoft's pages vary by country)
Established in: United States
Built for: Organisations with Exchange or Microsoft 365 mailboxes that rely on shared mailboxes and calendar scheduling
Not for: Anyone who wants an ad-free mailbox without a Microsoft subscription, or Linux desktop users
01
Why buyers look past Microsoft Outlook
01
The free version is paid for with ads
Microsoft's support page says ads sit in the inbox next to messages with an Ad label, that web users also get a larger display ad on the side, and that dismissing one does not stop it returning. The documented way out is a Microsoft 365 subscription. Switching personal mail to another client removes the ad slots, though the mailbox itself still lives at Microsoft unless you move the address.
02
New Outlook is not classic Outlook
Microsoft's own comparison table lists COM add-ins and VBA macros as not supported in the new Outlook for Windows, multiple mail profiles as upcoming, and offline use and .PST files as only partly available. Teams that built workflows on those pieces have to choose between staying on the classic app and finding a client with a different extension model.
03
Account coverage has gaps for office setups
Microsoft Learn says the new app supports Microsoft 365 work and school accounts, Outlook.com, Gmail, Yahoo, iCloud and other IMAP and POP accounts, while on-premises Exchange accounts are not supported. It also cannot reply or forward from a different account than the one the message arrived in. A small office on its own Exchange server or with many mailboxes meets these limits first.
Published subscription that funds development; trial runs 14 days of active use, then Free Mode
Keyboard-driven IMAP client for macOS from a Copenhagen studio
you are on a Mac, live in IMAP and want to search and sort mail by rules you write
#2
03
What each one does differently
1
Mozilla Thunderbird
Not stated by the vendor · Free to download and use; funded by user donations
Thunderbird has no price, no ad slot and no account to sign in to, and its source is published under the MPL 2.0 licence. The Outlook habits it does not copy are shared team inboxes and a vendor contract: support is a community forum and the project is funded by donations.
Switch from Microsoft Outlook if you want a free desktop client with no ads and no subscription behind it.
Czechia · Published; free tier for home use, yearly subscription or one-time licence; 30-day trial
eM Client sells the closest desktop imitation of the classic Outlook layout for Windows and macOS, with mail, calendar, contacts and tasks in one window. Pricing is published in euros: a free tier of two accounts, a yearly plan, or a one-time licence that covers only the current major version.
Switch from Microsoft Outlook if you want an Outlook-like desktop program that you can buy once instead of renting.
United States · Published; free tier with one account, Premium yearly or pay-once; 14-day money-back guarantee
Mailbird is a Windows and Mac client with a one-account free tier and a Premium plan priced around €4 a month when billed yearly. A pay-once option exists, but future major versions and the Leave Me Alone add-on cost extra. It has no Outlook-style server rules for Exchange.
Switch from Microsoft Outlook if you run several accounts on Windows and want a lighter app with an optional one-off payment.
Ukraine · Published; free tier, Plus and Pro per user monthly or yearly, Enterprise quoted; 7-day trial
Spark from Readdle adds comments and shared drafts to the mailbox so colleagues can write replies together, a thing Outlook does with separate shared mailboxes. Free covers unlimited accounts, Plus is €10 and Pro €22 per user monthly, and AI limits differ per plan.
Switch from Microsoft Outlook if colleagues draft and discuss replies together and you want a free starting point on every device.
Canada · Published per-user plans, billed yearly or monthly; 30-day trial without card
Missive treats the inbox as team space: conversations, tasks, internal comments, SMS and chat channels next to email, at $14, $24 or $36 per user monthly. It replaces Outlook's shared mailboxes with assignable threads, but a single user who only wants a reading window pays for features left unused.
Switch from Microsoft Outlook if several people answer the same mailbox and need to see who owns each thread.
Not stated by the vendor · Free version; Pro subscription with published monthly price
Mailspring runs on Linux as well as Mac and Windows, which Outlook's native apps do not, and its repository is licensed under GPL v3. Read receipts, link tracking and send later require Pro at $8 a month. A full calendar view is still announced as coming.
Switch from Microsoft Outlook if you use Linux or want a client whose code you can read, with paid tracking as an option.
Not stated by the vendor · Published; free tier, yearly or lifetime purchase; 7-day trial of paid features
Canary Mail ties one user licence to Mac, Windows, iOS and Android, with a free tier, Growth at $36 a year and Pro+ at $100 a year, and no monthly billing. PGP and SecureSend encryption start at Pro+. It has no shared inbox and no Exchange server administration.
Switch from Microsoft Outlook if one person needs the same client on four platforms, with encryption as an upgrade.
Not stated by the vendor · Published; yearly personal price or monthly per-user price for domains; 30-day trial without card
HEY does not manage your Outlook mailbox: it replaces it with a hey.com address or your own domain, at $99 a year for individuals or $12 per user monthly for domains. Unknown senders wait in a Screener, a model Outlook has no counterpart for, and Exchange cannot be connected.
Switch from Microsoft Outlook if you are willing to move the address itself and want unknown senders held back by default.
Not stated by the vendor · Published per-seat monthly plans, priced by AI tier; 14-day trial
Shortwave prices by AI capacity, with Premier at $45 and Max at $120 per seat monthly, and uses Claude models for search and drafting. It is built around Gmail accounts, so a mailbox on Microsoft 365 is the case to test before paying. Outlook's AI add-on is a separate Microsoft purchase.
Switch from Microsoft Outlook if your mail is Gmail and you want an assistant that searches and drafts inside the inbox.
United States · Published subscription, monthly or annual, per user or per group seat; 14-day trial without card
Mimestream is a native Mac program that speaks the Gmail API and nothing else: no Outlook, no Exchange, no IMAP. In exchange it reads Gmail labels and categories as Google defines them. It needs macOS 12 or newer and is sold by subscription only.
Switch from Microsoft Outlook if you moved your mail to Google Workspace and want a fast Mac client for it.
Denmark · Published subscription that funds development; trial runs 14 days of active use, then Free Mode
MailMate is a keyboard-driven IMAP client for macOS only, written in Copenhagen, where messages are composed in Markdown and smart mailboxes are built from search conditions. It has no calendar of Outlook's kind. After the trial it falls into Free Mode, which stamps outgoing mail.
Switch from Microsoft Outlook if you are on a Mac, live in IMAP and want to search and sort mail by rules you write.
Outlook stays the right choice when the mailbox is on Exchange or Microsoft 365 and the organisation leans on shared mailboxes, delegation, calendar scheduling across colleagues and administrator policies. Add-ins and macros built for the classic app keep working there. None of the other clients here replicates Exchange administration, so a company whose IT team manages mail through Microsoft's admin tools gains little by changing the window.
05
What moving off Microsoft Outlook involves
01
Keep the mailbox, change the window
Most of the clients on this page connect over IMAP, so mail stays on the server and the move is about the program. Check the protocol first: Mimestream and Shortwave are built for Google accounts, and Microsoft documents on-premises Exchange only through IMAP in its new app. Test one account for a week before removing Outlook.
02
Archives, rules and add-ins do not travel
Local .PST archives, client-side rules and COM add-ins are tied to the Outlook client. Import archives into an IMAP folder or keep a copy, rebuild rules in the new client, and list which add-ins staff actually use. The ones that touch a CRM or a billing system need a replacement before anyone switches.
03
Calendars are the part that breaks first
Several clients here are mail first and treat the calendar as optional: Mailspring says a full calendar is still coming, and MailMate has none of Outlook's. If meeting invitations and free-busy views matter, check each candidate's calendar against your own calendar service before you decide.
06
Questions about replacing Microsoft Outlook
6 answers
Is there a free alternative to Outlook?
Thunderbird is free to download and use, funded by donations, and runs on Windows, Linux and macOS.
Mailspring, eM Client, Mailbird, Canary Mail and Spark also have free tiers, each with limits such as account counts or paid tracking. Outlook itself is free on the web but shows ads until a Microsoft 365 subscription is added.
Which Outlook alternative works with Exchange?
Mailspring states that it connects Office 365 and IMAP mailboxes.
For eM Client, Mailbird, Spark and the others, confirm Exchange or Microsoft 365 support on the vendor's page before buying, because Mimestream and Shortwave are built around Google accounts. On-premises Exchange needs a test with your own server.
What is the difference between classic and new Outlook?
Classic Outlook is the long-standing Windows program with COM add-ins, VBA macros and multiple profiles.
The new Outlook for Windows is built on the Outlook web experience and does not support COM add-ins or VBA, per Microsoft's comparison table. Both names are still in use, so say which one you mean when you compare.
Which Outlook alternative suits a Mac?
MailMate and Mimestream are Mac only, one for IMAP and keyboard users and one for Gmail accounts. eM Client, Mailbird, Spark, Canary Mail and Mailspring also run on macOS.
Can I stop the ads in Outlook without leaving it?
Microsoft's support page says a Microsoft 365 subscription stops the ads, including for a free Outlook.com address once it is linked to the subscription.
Turning off ad personalisation does not remove them, it only changes how relevant they are. A third-party client avoids the slot entirely.
Which alternative is best for a team inbox?
Missive is built for shared conversations, with assignments and internal comments, and Spark adds shared drafts and comments. Thunderbird, Mailspring and MailMate are single-user programs. Outlook's own answer is the shared mailbox, so test whether an assignable thread suits your support or sales routine.
—
Sources
Checked 29 October 2026
Microsoft Support: About ads in Outlook: Ads in the free inbox, larger web display ad, Microsoft 365 subscription removes ads, personalisation switch does not.
Founder of The Knowledge Engineers and of 2 Steps Ahead, an AI search visibility agency. Editorially responsible for every page on this site; research and drafting are AI-assisted.
Written, edited and fact-checked by Sebastiaan Smits. Last reviewed
29 October 2026. How we review.
