The first and last version of Eudora OSE was released in 2010 to negative reviews and lukewarm support; development subsequently ceased due to a lack of funding.

Hermes, its maintainers, described Eudoramail 8.0 as currently being in alpha; Wellington typographer Jack Yan, meanwhile, points out its stability, a number of well-characterised and reproducible display bugs notwithstanding.

Rather than devote continued resources to the development of a loss leader product,[9][10] Qualcomm instead sponsored the creation of a new open-source version based on Mozilla Thunderbird, code-named Penelope, later renamed to Eudora OSE.

On May 22, 2018, after five years of discussion with Qualcomm, the Computer History Museum acquired full ownership of the source code, the Eudora trademarks, copyrights, and domain names.

[2] In August 2018, a "small team" started working on patching the lacunae in the Eudora code, in order to render it usable on modern systems.

According to the initial posting on the eudora-win[Note 1] mailing list, the intent was to decouple entirely from Stingray Desktop, a proprietary library designed for constructing graphical user interfaces under Windows.

[16] On 31 March 2022, it was announced that "HERMES Mail is on the launchpad and final preparations are made for liftoff",[17] with the initial alpha of Eudoramail 8.0 being released on Aug 1 2022.

[6] At the time, the stated policy was that it would be a soft launch, with the release being phased in first for testers, then for users on the eudora-win mailing list on the Clio ListMoms Cartel,[18] and finally for the public at large.

Eudora 7.0 added Indexed search (powered by X1 Discovery), which finds any emails using single or multiple criteria in seconds; due to lack of legal permissions, this feature is missing in Eudoramail 8.0 (unless a customer already has an existing copy of x1lib.dll , which can be placed into the program directory to restore X1 functionality).

Eudora is noteworthy for its extensive variety of settings to customize its behavior, many of which are not available in the user interface but are accessed using x-eudora-setting URIs that must be pasted into a message and clicked.