Download of Postie 1.0 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The actual developer of this software for Mac is Cryptix Studios LTD.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The program lies within Productivity Tools, more precisely Office Tools.
From the developer:
With this application you can easily write your posts in Markdown and then post directly to Scriptogram with Command P. Postie supports the Notification Center, to give you information on your post status. If you just type a filename in the text box at the top of the screen, you can then open or save a file of that name.
You may want to check out more software for Mac, such as 3dissue, Blurb Tally or Pads X, which might be related to Postie.