Recently, while reading this answer, I noticed that the links such as this one to gmane.org don't work. After searching around for a while, I was able to discover that these mailing list posts are still available at news.gmane.io if accessed through Gnus in Emacs, but there are two problems:

1. Setting this up is a huge nuisance (even now it still doesn't work 100% for me and sometimes needs a restart of Emacs to work again) and forces the user to stop using their web browser in order to access what should just be a hyperlink.

2. I could not find any translation from the old URLs to the place in the gmane archive where the relevant post should appear, so I just had to search by author and topic until I found (what I think is) the right one.

This problem is not limited to the answer I found above, other examples can be found by typing url:"*.gmane.*" into the search bar (of MathOverflow, not the MathOverflow Meta one right above here). So something needs to be done to make these old answers readable from the web again. What should it be?

• I will just mention that it is possible to include a direct link to the search. It seems that there are 14 posts on MO and 6 posts on Mathematics with such links. Comments with gmane.org 8 comments on MO and three on MSE. – Martin Sleziak May 23 at 14:19
• I emailed Bob Rosebrugh, the admin of the categories mailing list to which these links point, to see what the plans are for the post-2009 archive. Everything from 1990 to July 2009 is available here: mta.ca/~cat-dist/archive - perhaps an enterprising soul could extract out that info and host it somewhere in a nice format.... – David Roberts May 25 at 11:03
• More of a worry is references to specific 'categories' emails (once) hosted on gmane in published books! I found four on the first page of google search results... – David Roberts May 25 at 11:09

I've managed to find copies of 6 links in 5 posts which were archived in the Wayback Machine, and they have been updated (thanks for reviewing!)

I might have missed some, but the main challenge is that different versions of the link exist:

Other schemas might exist as well but I'm not familiar with gmane.

• Thanks for doing this. Of course, I tried this with the example from the question first, and when it failed, I (wrongly) assumed it wouldn't work for anything else. We still need a solution for the rest that are only accessible via NNTP through news.gmane.io. – Robert Furber May 24 at 1:00
• I'm not sure what the copyright on these things is, but you might be able to upload them somewhere else (for text-based files, I usually use gist.github.com). – Glorfindel May 24 at 9:17
• For those mystified by the end of Robert's comment, gmane itself has a new url, see: lars.ingebrigtsen.no/2020/01/15/… – David Roberts May 25 at 10:59

Since it seems that this is not common knowledge, I'll add an explanation of one way that gmane can still be accessed. I know there are some people knocking about here who were accessing email in Emacs long before Sir Tim had even thought of the WorldWideWeb, but I wasn't, and in fact I didn't have any idea how to do it until shortly before posting the question above. If you don't understand any of the following at all, you understand it at least as well as I do.

This should work on any unixy sort of system. Windows users may need to use something like Cygwin (but I haven't tried this).

1. If you don't have it, install Emacs. Current versions of Emacs include Gnus by default.
2. Create a file called .gnus.el in your home directory (the initial full stop is important). So it should appear as ~/.gnus.el.
3. Put the line (setq gnus-select-method '(nntp "news.gmane.io")) in it. If you want to make posts to mailing lists from Emacs you'll need to add more stuff about that (I've never done this).
4. Save .gnus.el and quit Emacs (if you've been using Emacs to do this). Open it up again (or for the first time).
5. Type alt-x gnus⏎. This starts Gnus and should put you straight into the *Group* buffer. If you've never used it before, the message No news is good news will appear.
6. To add a new group, when you are in the *Group* buffer, type U (this must be a capital, so shift-u) and then type in the name of the group followed by ⏎ (tab completion is supposed to work, but didn't work for me). For the categories mailing list, you would therfore type gmane.science.mathematics.categories⏎. In cases of doubt, you can verify that the newsgroup exists by looking at admin.gmane.io on the web.
7. You should end up back at the *Group* buffer and the group name is now visible there (and will be there forever, unless you delete it somehow). Put the typing cursor over it and press ⏎ to access the newsgroup. You will be asked how many articles you want. I just press ⏎ here and get all of them.
8. A new buffer will appear containing the archived posts. You can then search through posts using alt-s to search forwards and alt-r to search backwards. You can also filter by author, which is helpful if that information is given (I use the menus to do this). Unfortunately, I still don't know of any method of getting directly to the archived post from an old permalink.gmane.org link.
9. To access a post, put your typing cursor over it and press ⏎. A new buffer containing the post will then fill most of the lower part of the Emacs window, and you can change your typing cursor back and forth between the post's buffer and the mailing list's buffer using ctrl-x o or the mouse, as you would normally in Emacs.
10. You can copy text using ctrl-space, moving the typing cursor, then alt-w as you would normally in Emacs. In general everything you have in Emacs works as usual, e.g. creating files, pasting text into them, using ctrl-x b to change between buffers and so on.
11. Sometimes Gnus will just hang up for no apparent reason while retrieving a post or searching. If it does, type ctrl-g to cancel and then try the same thing again.
12. When you are finished, type q until you get back to the main screen of Emacs (you can do this once to get back to the *Group* buffer from the buffer of a particular mailing list). You will be asked if you are sure you want to quit, so press y if you are. Then use ctrl-x ctrl-c as usual to quit Emacs.

• FWIW, gmane.io uses NNTP and should be accessible using any Newsreader, not necessarily Gnus. (If you are familiar with the Pine or Mutt email programs, I would suggest slrn which has a similar interface.) – Willie Wong May 28 at 2:03