Old MindManager Community Forum posts available via Wayback (aka Internet Archive)
A limited number of old MindManager Community Forum posts are available via The Wayback Machine - or to give it its proper title, the Internet Archive.
They can be found here: MindManager Customer Community (archive.org)
The last nine pages or so of the forum and the posts they contain that were archived in by the Wayback crawler in mid to late 2020 can be accessed, along with a handful of much older pages that were archived in 2015/16 and earlier. This makes a total of several hundred posts. You can click the page index number at the bottom of the page to access older pages that were indexed at the same time, or click on the Wayback timeline at the top of the page to move to another date.
In the main the forum pages and individual posts retain the old forum formatting, but a few don't - these are very ugly, but still readable. It's also a bit hit-and-miss with uploaded images; sometimes they appear, and sometimes they don't. Somewhat perversely, it's the unformatted posts which seem to do a bit better in this regard.
Unfortunately there is no easy way to search these pages and posts, but you can you can at least scan through the titles to look at the ones you want. You can also download them and I suggest doing this if you particularly want to refer to a post later. The internet can be a tough environment, and even archived pages can be lost or overwritten.