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Qpopper was one of the oldest and most popular server implementations of POP3. As a free and open-source server distributed under BSD style license, it was a common choice for Internet Service Providers, schools, corporations, and other organizations. It was included in several Linux and Unix distributions.

Qpopper is no longer maintained. The final version was 4.1.0 released in 2011.

Qpopper was distributed by Qualcomm as source code; other parties offer pre-compiled or pre-configured versions for various platforms.

Qpopper ran on a wide variety of platforms, including virtually all Unix and Linux distribution,[1] Mac OS X, and even Windows under cygwin.

Qpopper was generally recognized as fast, stable, and secure. It was most commonly used with standard Unix mbox format inboxes (or "spools") but also supported homedir mail. Because mbox is a linear format in which messages are stored sequentially, Qpopper supports a number of optimizations to improve speed and scalability, including a cache file to maintain mailbox state between sessions, and several optional I/O techniques.


Qpopper started out as "popper" around 1989 at the University of California, Berkeley. Qualcomm took it over about 1993, and renamed it "Qpopper". Qualcomm's original goal was to promote the availability of correct and modern servers for the Eudora mail client to use, and also to provide a platform for newer extensions.


  1. ^ Blum 2001, p. 474: "The qpopper program is another MUA package that is frequently used on Unix servers. It differs from the UW package in that it only supports POP3 connections. However, its POP3 server has some extra features that make it attractive to mail administrators.
    qpopper is freeware originally released by the University of California at Berkeley, but now maintained by the Qualcomm corporation. It was written to provide POP3 server software for most types of Unix servers. It works just great on Linux mail servers.
    qpopper supports both the normal user/password POP3 logins and a special APOP POP3 encrypted authentication. By default, the user/password login method sends usernames and passwords across the network in clear text format.
    The user/password login feature supports using the standard Linux password files, as well as a special feature for Linux shadow password files. The APOP feature supports encrypted passwords using a separate password database file that the mail administrator must maintain separately."


  • Blum, Richard (2001). Postfix. SAMS.