Sylpheed
What Sylpheed is
Sylpheed is free desktop email software for beginners through power users, with offline access on Linux, macOS, Windows, BSD, and other Unix-like systems. It supports POP3, IMAP4rev1, SMTP, and NNTP, plus IPv6. SSL/TLSv1 connections are available for POP3, IMAP4, and NNTP, and GnuPG can optionally sign or encrypt messages. Filters can inspect headers, message bodies, size, date, and flag status; saved searches become search folders. Messages use MH storage, one file per message, which the maker says assists backup, migration, and processing by other applications. Junk-mail handling calls external tools such as bogofilter or bsfilter, and fetchmail or procmail can help receive mail. Other external commands support filtering and composition. An optional plugin creates encrypted ZIP attachments and a password-notification email, requiring Sylpheed 3.5.1 or later and 7-Zip. The maker says Sylpheed is translated into 30 languages. Version 3.7 is listed as stable, while 3.8beta1 is the development release. The mailing list ended in 2025; GitHub Issues is suggested for sharing information and reporting bugs. Sylpheed is GNU GPL software, with its library under GNU LGPL.
Who it suits
Sylpheed suits desktop users who want offline email, broad mail-protocol support, filtering, and optional encryption. It can also suit users who rely on external mail-processing tools.
What it does well
- Works offline on major desktop systems
- Supports POP3, IMAP4rev1, SMTP, and NNTP
- Optional GnuPG signing and encryption
- Searches can become folders
- Translated into 30 languages
What to know first
- Stable version dates to January 2018
- Mailing list discontinued in 2025
- Attachment plugin requires 7-Zip and Sylpheed 3.5.1+
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Sylpheed | GNU GPL software; no price stated | Free |
As sylpheed.sraoss.jp lists them, read 12 Oct 2026. The maker's own page has the final word.
Verdict
Sylpheed provides a focused, free desktop mail client with extensive protocol, filtering, storage, and external-command support. Its older stable release and discontinued mailing list are important considerations.
Facts from Sylpheed's own pages
- App coverage
- desktop · sylpheed.sraoss.jp, 21 Sept 2026
- Attachment encryption plugin
- An optional plugin automatically packages outgoing attachments as encrypted ZIP files and creates a password notification email; it requires Sylpheed 3.5.1 or later and 7-Zip. · sylpheed.sraoss.jp, 12 Oct 2026
- Email security
- It optionally supports GnuPG message signing and encryption, and SSL/TLSv1 connections for POP3, IMAP4, and NNTP. · sylpheed.sraoss.jp, 12 Oct 2026
- Filtering and search
- Filters can match headers, message body, size, date, and flag status, and search results can be saved as search folders. · sylpheed.sraoss.jp, 12 Oct 2026
- Free plan
- Yes · sylpheed.sraoss.jp, 21 Sept 2026
- Integrations
- Sylpheed can call external commands for filtering and message composition, and can work with fetchmail or procmail for receiving mail. · sylpheed.sraoss.jp, 12 Oct 2026
- Junk mail
- Junk mail control uses external commands, including bogofilter and bsfilter, and can use other programs as well. · sylpheed.sraoss.jp, 12 Oct 2026
- Languages
- The maker says Sylpheed is translated into 30 languages and includes internationalized line wrapping in its editor. · sylpheed.sraoss.jp, 12 Oct 2026
- License
- The maker describes Sylpheed as free software distributed under the GNU GPL, with its library part under the GNU LGPL. · sylpheed.sraoss.jp, 12 Oct 2026
- Mail protocols
- It supports POP3, IMAP4rev1, SMTP, and NNTP, as well as IPv6. · sylpheed.sraoss.jp, 12 Oct 2026
- Offline access
- Yes · sylpheed.sraoss.jp, 21 Sept 2026
- Product
- Sylpheed is a lightweight, user-friendly email client designed for beginners through power users. · sylpheed.sraoss.jp, 12 Oct 2026
- Release status
- The site lists version 3.7 as stable, updated 31 January 2018, and version 3.8beta1 as the development version, updated 14 September 2022. · sylpheed.sraoss.jp, 12 Oct 2026
- Storage
- Messages use MH format, with one file per message, which the maker says helps with backup, migration, and processing by other applications. · sylpheed.sraoss.jp, 12 Oct 2026
- Support
- The Sylpheed mailing list was discontinued in 2025, and the maker points users to GitHub Issues for information sharing and bug reports. · sylpheed.sraoss.jp, 12 Oct 2026
- Supported systems
- The maker lists Windows, Linux, BSD, Mac OS X, and other Unix-like systems; its requirements page specifies Windows 7/8.1/10 or Linux or another POSIX-compliant Unix-like OS. · sylpheed.sraoss.jp, 12 Oct 2026
Where Sylpheed stands on Freedom251
- Email clients#57 of 142