KMail
KMail: A mature, configurable Linux email client with broad protocols and offline access. Ranked #5 of 142 in Email Clients by our editors (8.9/10); pricing: Free plan; best for linux users wanting a mature open-source client.
At a glance
- Editor score8.9 / 10
- PricingFree plan
- Best forLinux users wanting a mature open-source client
- Free planYes
- Paid fromFree
- App coverageDesktop
- Facts checked21 Sep 2026
Where it wins
- Supports IMAP, POP3, SMTP and Microsoft Exchange
- OpenPGP, PGP/MIME and S/MIME support
- Offline access, filtering, search and scheduled sending
Where it doesn't
- Available on Linux rather than across multiple operating systems
- Unified mailbox requires a plugin disabled by default
- Desktop-focused app coverage
Our verdict on KMail
KMail is an open-source desktop email client developed within the KDE community. It is designed for Linux users who want a configurable application for managing multiple mail accounts locally. The client supports IMAP, POP3, SMTP and Microsoft Exchange, with offline email access and optional local synchronization. Its feature set also includes message filtering, local and remote search, tagging, flagging, mailing-list management, spam-checker integration and scheduled email sending. KMail is distributed as KDE software under GPL-2.0-or-later and is available as free open-source software.
Its strongest fit is for users who value protocol coverage, local control and integration with the KDE ecosystem. KMail connects with KOrganizer, KAddressBook and Akonadi, while SpamAssassin and Bogofilter support spam-checking workflows. Encryption support covers OpenPGP, PGP/MIME and S/MIME. Unified mailbox folders are available through a plugin, although that plugin is disabled by default. These capabilities make KMail suited to people who want detailed account management, offline access and configurable message organization rather than a minimal webmail-style interface.
KMail is a clear choice for Linux users who want a long-established, open-source desktop client with broad mail support and a substantial set of organization tools. Scheduled sending, unified folders, search and filtering support more structured email workflows, while KDE integrations can suit users already working with related applications. It is less suitable for people seeking a client across multiple platforms or a desktop-and-mobile product. Users choosing KMail should also expect to review KDE’s available integrations and enable the unified mailbox plugin if that workflow is important.
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KMail pricing
KMail fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| App coverage | Desktop |
| Account limit | Not verified |
| Unified inbox | Yes |
| Offline access | Yes |
| Scheduled sending | Yes |
| Calendar tools | Yes |
| Deployment | Desktop |
| Platforms | Linux |
| Support | Email, Live chat, Community, Docs |
| Built for | Solo, Small business, Mid-market (editorial estimate) |
| Integrations | 4 integrations: KOrganizer, KAddressBook, SpamAssassin, Bogofilter |
| Pricing | Free plan |
| Website | apps.kde.org |
| Facts checked | 21 Sep 2026 |
KMail integrations
KMail lists 4 integrations on its own site.
- KOrganizer
- KAddressBook
- SpamAssassin
- Bogofilter
Alternatives to KMail
- Mozilla ThunderbirdA capable free client for multi-account email, offline access, and desktop productivity tools.9.4
- Zoho MailA flexible hosted email service with free access, migration tools, and Zoho collaboration options.9.2
- Apple MailA capable Apple-focused email client with unified inboxes, scheduling, privacy controls, and AI assistance.9.1
KMail vs the competition
- KMail vs Mozilla Thunderbird
- KMail vs Zoho Mail
- KMail vs Apple Mail
- KMail vs Spark Mail
- KMail vs eM Client
- KMail vs Roundcube
Compare KMail with any tool side by side →
Also Ranked In
KMail is ranked in 2 of our directories.
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Featured on iTechGuides
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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