Claws Mail is a lightweight desktop email and news client with a plugin system that adds spam filtering, encryption, feed reading, and calendaring. It suits users who want fast mail handling on modest hardware and full control over every part of the setup.
Claws Mail is an email and news client that handles multiple accounts, threaded conversations, filtering, and Usenet news while staying fast on older machines. Setup follows the usual pattern: define an account, choose a mailbox format, and start receiving mail, with the option to add more accounts later and keep each one's folders separate. Filters and processing rules run on arrival, color labels and tags make important threads visible, and the search function scans folders rather than a single inbox. Everything from toolbars to fonts to the quotation characters used in replies can be adjusted, and a permanent log window records what the program is doing.
The plugin architecture is where most of the extra capability lives. Rather than bloating the core application, Claws Mail ships a large collection of add-ons that can be enabled individually: spam scanners such as Bogofilter, SpamAssassin, and Bsfilter, antivirus checking through ClamAV, a Sieve filter manager for servers that support it, an RSS and Atom feed reader, HTML and PDF viewers, and a calendar that handles vCalendar messages and webCal subscriptions. That modular approach keeps the base program small and lets you decide how much you want installed. Compare it with something like Betterbird, which starts from a much larger foundation and inherits a different set of trade-offs.
The reason Claws Mail has kept a following for decades is that it does the fundamentals well and refuses to get in the way. It starts quickly, handles mailboxes with tens of thousands of messages without complaint, supports several mailbox formats, and lets you work entirely from the keyboard if that is how you prefer to read. Message scoring is the feature people miss when they leave: the program learns from the messages you mark and adjusts scores automatically, which quietly buries unwanted mail without requiring hand written rules. Privacy tools are first class, with GnuPG, PGP inline, and PGP/MIME plugins plus S/MIME support, and on the fly switching between inline and MIME signing in the compose window. Smaller touches accumulate: reply to part of a message, attachment warnings, an address harvester, LDAP recipient completion, per folder properties, and full message coloration for quoted text. Add-ons cover whatever is missing, from feeds and calendars to antivirus scanning.
Key capabilities and highlights.
Several mail accounts in Claws Mail can run side by side, each with its own folders, identity, and server settings, and mail can be stored in MH folders, unix mailspool, or mbox files. Import and export tools let you move between those formats without reaching for an external converter.
Filters test incoming and outgoing mail against detailed conditions and then move, copy, delete, forward, or run external commands, while per folder processing rules decide what happens as messages land. Templates speed up recurring replies, and Actions apply the same conditions on demand to selected messages.
Claws Mail adjusts a numeric score on each message based on how you have treated similar mail before, so unwanted senders sink down the list without a rule being written for every one. Dedicated plugins add Bogofilter, SpamAssassin, or Bsfilter scanning, with the option to delete spam or file it away for review.
Separate Claws Mail plugins handle PGP core functions, PGP inline, PGP/MIME, and S/MIME, so signing, verifying, encrypting, and decrypting all happen inside the normal reading and composing windows. The signing method can be switched while a message is being written, and SSL certificate management is built into the client.
Search runs across whole mailboxes with a wide choice of conditions, and results appear in a dedicated list where they can be acted on directly. Combined with color labels, tags, and the option to hide read messages, a crowded mailbox becomes something you navigate deliberately rather than simply scroll through.
The Claws Mail plugin mechanism covers far more than mail: a feed reader for RSS and Atom, a vCalendar plugin with calendar support and webCal subscriptions, PDF and PostScript viewing, HTML viewers, notification and tray alert plugins, an archiving helper, and a Sieve manager for servers that support it.
Toolbars, fonts, colors, layout, message coloration, and the quotation characters used when replying are all configurable, and themes can restyle the whole window. A log window records activity, keyboard shortcuts cover nearly every action, and folders can be displayed in whatever arrangement suits your reading habits.
The Claws Mail address book imports from LDIF, Mutt, and Pine, exports in several formats, and can complete recipients as you type, including through an LDAP directory. It can also harvest addresses from incoming mail automatically, which gradually builds a usable contact list out of ordinary correspondence.
Browse historical releases and previous builds.
Common questions about Claws Mail.
It is a lightweight desktop email and news client built around a plugin architecture. It handles multiple accounts, filtering, threaded reading, GnuPG and S/MIME encryption, Usenet news, and search, and it can be extended with add-ons for feeds, calendars, spam scanning, and document viewing.
Yes, it is free and open source software, distributed at no cost with no subscription, advertising, or paid edition. Support comes from documentation, wikis, and user mailing lists rather than a commercial helpdesk with a service agreement.
It retrieves and sends mail over POP3, IMAP4rev1, and SMTP, reads and posts Usenet news over NNTP, and can also work with local unix mailspool plus mbox or MH folders. SSL and TLS are supported across those protocols so connections can be encrypted.
Yes, through Claws Mail plugins. Core PGP functions, PGP inline, and PGP/MIME are handled by separate add-ons, S/MIME has its own plugin, and the compose window lets you change the encryption or signing method on the fly. GnuPG must be installed for the PGP plugins to work.
Two mechanisms in Claws Mail work together. Message scoring learns from how you classify mail and adjusts each message's score accordingly, while plugins can hand messages to Bogofilter, SpamAssassin, Bsfilter, or ClamAV. You can choose to delete anything flagged or move it to a folder for later review.
The default display is plain text for speed and safety, and HTML viewing arrives through optional plugins, including a WebKit based renderer, a lightweight renderer, and an external viewer. Because viewing is a plugin, HTML can stay disabled for untrusted senders without losing the ability to read newsletters.
Yes, it continues to receive releases and plugin updates, and the project hosts its own source distribution and documentation rather than relying on a public code hosting platform. Long-time users on the project mailing lists remain the main source of day to day help.
Claws Mail is a lightweight desktop email and news client with a plugin system that adds spam filtering, encryption, feed reading, and calendaring. It suits users who want fast mail handling on modest hardware and full control over every part of the setup.
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