GNUMail is a free and open-source, cross-platform e-mail client based on GNUstep and Cocoa. It is the official mail client of GNUstep and is also used in Étoilé. It was inspired by NeXTMail (NeXT's Mail.app), the predecessor of Apple Mail. GNUMail is based on the mail handling framework Pantomime. GNUMail demonstrated that it is possible to develop cross platform programs for GNUstep and Cocoa. Features Supported protocols: POP3 (with APOP support), IMAP4 and UNIX; SMTP Supports TLS with all protocols Mail spool file support for receiving File formats for local saving: Maildir, Berkeley mbox Filters for incoming and outgoing mail which support regular expressions Thread Arcs for email thread visualization and navigation Find Panel supporting regular expressions Ability to add custom mailheaders Native support for PGP/GPG encryption See also Comparison of email clients References External links GNUMail User Guide for Version 1.0pre1. GNUMail.app - GNUstepWiki Email client software for Linux MacOS email clients Free email software Unix Internet software Portable software Free software programmed in Objective-C Software that uses GNUstep