Terminal Email

S-nail vs Sup

S-nail: Command-line mail program that implements POSIX mailx, with MIME, IMAP, POP3, SMTP, Maildir and S/MIME support.
Sup: Curses email client in Ruby built around threads, labels and fast full-text search over local mail.

Differences

Side by side

S-nailSup
InterfaceCommand-line tools and promptsFull-screen terminal interface
LanguageCRuby
LicenseISC and BSD 2-Clause and BSD 3-Clause and BSD 4-ClauseGPL 2.0 or later
Latest version14.9.251.4
LinuxNativeNative
macOSNativeNative
WindowsThrough WSLThrough WSL
BSDNativeBuild from source
AndroidNoNo
IMAPYesNo
POP3YesNo
SMTPYesThrough a separate tool
JMAPNoNo
MaildirYesYes
mboxYesYes
notmuchNoNo
OpenPGPNoYes
S/MIMEYesNo
OAuth2 sign-invia scriptNo
ThreadsYesYes
Searchbuilt-in message specifications and the search command; IMAP SEARCH on IMAP foldersXapian full-text index with a query language
HTML mailbuilt-in tag-soup filter or external viewer via mailcapvia the mime-decode hook and an external viewer such as w3m
MouseNoNo
Multiple accountsYesYes
Offline useIMAP cache with disconnected modereads local Maildir or mbox; sync with isync or OfflineIMAP
CalendarNoNo
Contactsaliases via the alias commandtracks recent contacts automatically
Vim-style keysNoYes
Configuration~/.mailrc command file~/.sup/config.yaml and ~/.sup/sources.yaml, plus Ruby hooks

Which to choose

Choose S-nail for

  • Drop-in POSIX mailx, so it works in existing shell scripts and cron jobs.
  • Built-in SMTP, POP3 and IMAP with TLS; no separate sync or send tool needed.
  • S/MIME signing and encryption are built in.

Watch out for

  • Line-oriented prompt instead of a full-screen interface.
  • No built-in OpenPGP; upstream documents a gpg pipe workaround only.
  • IMAP support is kept at an older code level and upstream advises care.

Install S-nail

Choose Sup for

  • Fast full-text search over large archives
  • Gmail-style labels, archiving and muting of threads
  • Ruby hooks for custom behavior

Watch out for

  • No built-in IMAP or SMTP; needs isync (or similar) and msmtp
  • Changes sync back to Maildir only with the optional sync-back setting
  • Packaged by Debian and Ubuntu (and the AUR); elsewhere installed as a Ruby gem with native Xapian bindings

Install Sup

Questions

What is the difference between S-nail and Sup?

S-nail is a command-line program; Sup is a full-screen terminal client. Only S-nail has built-in IMAP, POP3 and SMTP. On BSD, S-nail runs natively and Sup builds from source.

Which runs on Windows, S-nail or Sup?

On Windows, S-nail runs through WSL. On Windows, Sup runs through WSL.

See also: S-nail alternatives, Sup alternatives.