Last Updated on March 15, 2026
Sylpheed is a simple, lightweight and featureful e-mail client based on the GTK+ GUI toolkit. It aims to combine a quick and responsive client, with a sophisticated interface, intuitive operation, as well as an abundant feature set.
Sylpheed uses a 3-paned display similar to the popular e-mail clients for Windows such as Outlook Express and Becky. Many commands are accessible with the keyboard like the Emacs-based mailers such as Mew and Wanderlust. This enables users to easily migrate to Sylpheed.
It stores mail in the MH Message Handling System.
It supports the following protocols: POP3, IMAP4rev1, SMTP, NNTP, SSL/TLSv1 (POP3, SMTP, IMAP4rev1, NNTP), IPv6.
Key Features
- Multiple accounts.
- Powerful filtering (POP3, IMAP4, local spool).
- Powerful search (query search, quick search, search folder).
- Junk mail control.
- Thread display.
- Display and transfer of attachments by MIME.
- Inline image display.
- News reader.
- SMTP AUTH support (PLAIN / LOGIN / CRAM-MD5).
- CRAM-MD5 authentication (SMTP AUTH / IMAP4rev1).
- APOP authentication (POP3).
- PGP signature / encryption (requires GPGME).
- Spell checking (requires GtkSpell).
- X-Face display.
- User-defined headers.
- Mark / color label.
- Mew/Wanderlust compatible key bind.
- Multiple MH folder support.
- mbox importing / exporting.
- Action function to work with external commands.
- External editor.
- Message queueing.
- Automatic mail checking.
- Draft message.
- Template.
- Line-wrapping.
- Autosave.
- Clickable URI.
- Address book.
- Newly arrived and unread message management.
- Printing.
- Offline mode.
- Tray icon (minimize to tray icon, new mail notification).
- Customization of toolbar.
- Remote operation by command line.
- Per-folder configuration.
- LDAP, vCard, and JPilot support in address book.
- CSV, LDIF file import in address book.
- Drag & Drop.
- Autoconf, automake support.
- Internationalization of messages by gettext.
- m17n (multilingualization) support.
Website: sylpheed.sraoss.jp
Support: Documentation, Mailing List
Developer: Hiroyuki Yamamoto and contributors
License: GNU General Public License v2.0
Sylpheed is written in C. Learn C with our recommended free books and free tutorials.
Related Software
| Graphical Email Clients | |
|---|---|
| Thunderbird | Popular free, cross-platform e-mail, RSS and newsgroup client |
| Kmail | Email component of Kontact |
| Sylpheed | Simple, lightweight client |
| Mailspring | New version of Nylas Mail |
| Claws Mail | Lightweight yet powerful and full-featured client |
| Evolution | Provides integrated mail, addressbook and calendaring functionality |
| Geary | Mail client for GNOME written in Vala |
| Astroid | Lightweight and fast Mail User Agent |
| Balsa | Email client for GNOME |
| Also known as Pantheon Mail | |
| Dodo | Based on the command line email swiss-army-knife notmuch |
| Aerion | Standalone lightweight e-mail client inspired by Geary |
Read our verdict in the software roundup.
| Lightweight Email Clients | |
|---|---|
| Sylpheed | Client also based on the GTK+ GUI toolkit |
| Claws Mail | Powerful, user-friendly, fast and full-featured mail client based on GTK+ |
| Geary | Lightweight mail client for GNOME that is written in Vala |
| Astroid | Lightweight and fast Mail User Agent |
| Trojitá | Qt-based IMAP email client |
| Aerion | Lightweight e-mail client inspired by Geary |
Read our verdict in the software roundup.
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there is one unique thing abut sylpheed: it stores every email in a separate file, so there’s never that “compress folders” thing (with the associated risk of something crashing while compressing, and finding yourself with all your emails lost)
I’ve used many MUIs that manage messages in the MH format. Sylpheed is hardly unique in that respect. For example, Mutt supports reading and writing four different mailbox formats: mbox, MMDF, MH and Maildir.