The 1.0.1 version of PostboxExpress for Mac is provided as a free download on our website. The most popular version among the application users is 1.0. This app's bundle is identified as com.postbox-inc.postboxexpress. This software for Mac OS X is an intellectual property of Postbox, Inc. The application lies within Communication Tools, more precisely E-mail.
From the developer:
Postbox is a fully featured email solution that provides powerful search, organization, and productivity tools for busy professionals.
You may want to check out more software for Mac, such as Hogwasher, Portable Thunderbird or Serial Mail, which might be similar to PostboxExpress.