The best Contact Manager alternative to Thunderbird is Evolution, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Thunderbird and six of them are Contact Managers so hopefully you can find a suitable replacement. Other interesting Contact Manager alternatives to Thunderbird are Flectar Mail, Koma-Mail, Clyton and sup.
Evolution is a personal information management application that provides integrated mail, calendaring, address book and task list functionality.
United States
Built from the ground up for speed. Flectar Mail delivers native performance, instant startup, and as little as 20 MB of RAM.
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Koma-Mail is an email client which is comfortable and has very handy functions. It does not need an installation, so that you can run Koma-Mail from your flash drive but, of course, also on your desktop.
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Clyton is an email client with advanced security and spam filtering features. Although priced for the general public, Clyton possesses the reliability and security required by businesses.
United States
Sup is a console-based email client for people with a lot of email. It supports tagging, very fast full-text search, automatic contact- list management, custom code insertion via a hook system, and more.
Hylki is a fast, GNOME-native email client with a three-pane layout, unified inbox, and support for OAuth accounts. Fast to open, effortless to read, and private by default.
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