Since the old NNTP forums are long gone, and the according archive website nntp-archive.sybase.com has no builtin search facility, I follow Jason's advice to search within the archive, as discussed in Breck's blog article " The Newsgroups Are Gone".
That works well enough for my needs.
However, the displayed URLs look weird (or even invalid...) and cannot be used as links within this forum, as shown in that answer...
Similar strange links are shown (for me) when searching for the following keywords:
"passthrough mode" site:http://nntp-archive.sybase.com
So what must I do to receive an useful link to the archived articles?
If you make the link using the Markdown syntax, it will work if you replace the
Text with a [link to nntp]
This looks like:
Text with a link to nntp
It also seems to work if you just include the plain URL itself. But for some reason, simply including the link in an