Sup

Free plan LinuxMac

What Sup is

Sup is a free, open-source console email client designed for people handling large amounts of mail. It combines mbox and Maildir sources, organizes messages into hierarchical threads with multiple tags, and provides a fast local full-text index with query predicates for message-body searches. Multiple accounts are supported, with the matching SMTP server, signature, and sender address selected when replying. Ruby hooks let users add custom handling for message types and text. Sup also tracks recent contacts, supports user-defined labels, and has full GPG support. It runs on Linux and macOS; instructions also cover Debian, Ubuntu, Fedora, Arch Linux, FreeBSD, and OpenBSD, while Windows is unsupported. The project is licensed under GPL version 2 or later. Maintainers describe it as mature and production-quality, focusing on preserving its current feature set. Sup may not work smoothly alongside other mail clients, and changes may not fully synchronize back to the mail source.

Who it suits

Sup suits experienced desktop users who prefer a console workflow, local search, threaded organization, and customizable Ruby hooks. It is aimed at Unix-like systems rather than Windows and may be difficult to combine with another mail client.

What it does well

Fast local full-text email search
Hierarchical threads with multiple tags
Multiple account support
Ruby customization hooks
Full GPG support

What to know first

Windows is not supported
May not synchronize all changes
May conflict with other mail clients
Console-based interface

Plans

Plan	Billed and limits	Price
Sup	GPL-2.0 licensed email client	Free

As supmua.dev lists them, read 12 Oct 2026. The maker's own page has the final word.

Verdict

Sup offers deep local organization and customization for users comfortable with console email tools. Its platform limits and imperfect synchronization with other clients should be considered before adoption.

Facts from Sup's own pages

Accounts: It supports multiple accounts and selects the corresponding SMTP server, signature, and sender address when replying. · supmua.dev, 12 Oct 2026
App coverage: desktop · supmua.dev, 20 Sept 2026
Contacts and labels: Sup tracks recent contacts and supports user-defined labels. · supmua.dev, 12 Oct 2026
Customization: Ruby hooks can add custom code to handle message types or text within messages. · supmua.dev, 12 Oct 2026
Integrations: The project wiki documents mail retrieval through OfflineIMAP, mbsync/isync, and Fetchmail, and sending through msmtp, putmail, and sendEmail. · github.com, 12 Oct 2026
Latest listed release: The releases page lists sup-1.4.gem dated 21 April 2026. · supmua.dev, 5 Oct 2026
License: The repository says Sup is free software under the GNU General Public License, version 2 or later. · github.com, 5 Oct 2026
Limitation: Sup may not work smoothly alongside other mail clients because not all changes can be synchronized back to the mail source. · github.com, 12 Oct 2026
Mail-client compatibility: The repository README says Sup generally does not work smoothly with other mail clients and that not all changes sync back to the mail source. · github.com, 5 Oct 2026
Mail sources: It handles mail from multiple mbox and Maildir sources. · github.com, 12 Oct 2026
Maintenance: The maintainers describe Sup as mature and production-quality, focus on preserving its current feature set, and welcome bug-fix and compatibility pull requests. · github.com, 12 Oct 2026
Platform support: The wiki lists Debian/Ubuntu, Fedora, Arch Linux, macOS, FreeBSD, and OpenBSD installation guidance and says Windows is not supported. · github.com, 12 Oct 2026
Privacy: The feature list states that Sup supports GPG. · supmua.dev, 12 Oct 2026
Product: Sup is a console-based email client for people with a lot of email. · supmua.dev, 12 Oct 2026
Search: It provides a local full-text index and searches message bodies using a query language. · supmua.dev, 12 Oct 2026
Security: The security guide cautions that attachment content-type and filename metadata are sender-controlled and should not be used uncritically in commands. · github.com, 5 Oct 2026
Support: The project directs bug reports to its GitHub issue tracker and provides a mailing list for general discussion, development, and announcements. · github.com, 12 Oct 2026
Threaded email: It displays hierarchical email threads that can have multiple tags. · supmua.dev, 12 Oct 2026
Threads and tags: It organizes messages into hierarchical threads that can have multiple tags. · supmua.dev, 5 Oct 2026

Where Sup stands on Freedom251

Email clients#101 of 142