The Eternal-September server (https://www.eternal-september.org/) seems
to be the only viable alternative to post to usenet anonymously. Of
course, to keep it running you need to make a donation and abide by
their terms of use:
https://www.eternal-september.org/index.php?showpage=terms

The process is slightly involved, but is worth it:

1. First register on the only free usenet server left standing:

https://www.eternal-september.org/RegisterNewsAccount.php?language=en

You must do this using the Tor Browser:
https://www.torproject.org/download/

2. Download an older version (version 52.x.x or 60.x.x) of thunderbird
that is compatible with torbirdy (described in the next step). This is
done by modifying the version number in the thunderbird download link as
described here: https://support.mozilla.org/en-US/questions/1347599

3. Disable the internet and then install the older torbirdy-compatible
version of thunderbird. Before enabling the internet, disable updates:
[menu-bar] -> Edit -> Preferences -> Advanced -> Updates -> "Never check
for updates (not recommended: security risk).

Next go to [menu bar] -> Tools -> Add-ons -> Get Addons, search for
TorBirdy and install it.

Additional info on the TorBirdy Mozilla Thunderbird extension is here:

https://gitlab.torproject.org/legacy/trac/-/wikis/torbirdy

or tor onion link:

http://eweiibe6tdjsdprb4px6rqrzzcsi22m4koia44kc5pcjr7nec2rlxyad.onion/legacy/trac/-/wikis/torbirdy

Check that TorBirdy is up and Thunderbird is connected via Tor:

[menu-bar] -> Tools -> Add on preferences -> torbirdy -> Test proxy settings

For TorBirdy to work, you must be running Tor Browser simultaneously.

4. Thunderbird main page -> Set up an account -> Newsgroups. You will
need the info here:

https://www.eternal-september.org/index.php?showpage=techinfo

5. View Settings for this account -> Server Settings -> Always request
authentication when connecting to this server. See:

https://www.eternal-september.org/index.php?showpage=faq#Login-No-Auth

6. Account -> Subscribe (to newsgroups)

7. Get Messages and start reading and posting.

8. If you get "Login failed. Could not access eternal-september.org with
user id ..." or similar pop-up-window messages, then you should contact
the server admin and ask to enable access via Tor for your UserID:

https://www.eternal-september.org/index.php?showpage=contact&language=en

--------
I hope this helps some of the privacy conscious old timers like Odd
Bodkin get back on usenet.

Aether Regained:
> The Eternal-September server (https://www.eternal-september.org/) seems
> to be the only viable alternative to post to usenet anonymously.

What an irony, the choice of the name "eternal september" for a free
usenet server today!

Given the relative complexity of using usenet compared to the popular
alternatives (reddit, fb, etc.) eternal september has long ago come to
an end. Now, there are only a few die hard users on usenet. Hopefully,
the quality of the discussions will increase.

For the deplatformed, there are only a few avenues left for free,
unhindered discussion today:

- Usenet
- Substack
- Mastodon

Substack seems to already be under attack and Mastodon is the new kid on
the block. But, from what I can tell, Mastodon seems to be just a more
full-featured option to the text-only (free) usenet.

What a joke google groups has become. The stated purpose for
discontinuing Usenet syncing is:

https://support.google.com/groups/answer/11036538?visit_id=638417177590063709-2694786229&p=usenet&rd=1
> Why is Google Groups support for Usenet ending?
>
> Over the last several years, legitimate activity in text-based Usenet
groups has declined significantly because users have moved to more
modern technologies and formats such as social media and web-based
forums. Much of the content being disseminated via Usenet today is
binary (non-text) file sharing, which Google Groups does not support, as
well as spam.

If that is so, why not continue to support text-only news groups? Also,
check where the spam is coming from. FIFTEEN pages (30 posts/page) of
spam that I don't see on any usenet reader but only on google groups.

Sundar Pichai, wake up and smell the coffee!

Aether Regained:
> The Eternal-September server (https://www.eternal-september.org/) seems
> to be the only viable alternative to post to usenet anonymously. Of
> course, to keep it running you need to make a donation and abide by
> their terms of use:
> https://www.eternal-september.org/index.php?showpage=terms
>
> The process is slightly involved, but is worth it:
>
> 1. First register on the only free usenet server left standing:
>
> https://www.eternal-september.org/RegisterNewsAccount.php?language=en
>
> You must do this using the Tor Browser:
> https://www.torproject.org/download/
>
> 2. Download an older version (version 52.x.x or 60.x.x) of thunderbird
> that is compatible with torbirdy (described in the next step). This is
> done by modifying the version number in the thunderbird download link as
> described here: https://support.mozilla.org/en-US/questions/1347599
>
> 3. Disable the internet and then install the older torbirdy-compatible
> version of thunderbird. Before enabling the internet, disable updates:
> [menu-bar] -> Edit -> Preferences -> Advanced -> Updates -> "Never check
> for updates (not recommended: security risk).
>
> Next go to [menu bar] -> Tools -> Add-ons -> Get Addons, search for
> TorBirdy and install it.
>
> Additional info on the TorBirdy Mozilla Thunderbird extension is here:
>
> https://gitlab.torproject.org/legacy/trac/-/wikis/torbirdy
>
> or tor onion link:
>
> http://eweiibe6tdjsdprb4px6rqrzzcsi22m4koia44kc5pcjr7nec2rlxyad.onion/legacy/trac/-/wikis/torbirdy
>
> Check that TorBirdy is up and Thunderbird is connected via Tor:
>
> [menu-bar] -> Tools -> Add on preferences -> torbirdy -> Test proxy settings
>
> For TorBirdy to work, you must be running Tor Browser simultaneously.
>
> 4. Thunderbird main page -> Set up an account -> Newsgroups. You will
> need the info here:
>
> https://www.eternal-september.org/index.php?showpage=techinfo
>
> 5. View Settings for this account -> Server Settings -> Always request
> authentication when connecting to this server. See:
>
> https://www.eternal-september.org/index.php?showpage=faq#Login-No-Auth
>
> 6. Account -> Subscribe (to newsgroups)
>
> 7. Get Messages and start reading and posting.
>
> 8. If you get "Login failed. Could not access eternal-september.org with
> user id ..." or similar pop-up-window messages, then you should contact
> the server admin and ask to enable access via Tor for your UserID:
>
> https://www.eternal-september.org/index.php?showpage=contact&language=en
>
> --------
> I hope this helps some of the privacy conscious old timers like Odd
> Bodkin get back on usenet.
>

The procedure described in the OP shows how to route Thunderbird's net
traffic through Tor using the TorBirdy extension, which as of current
testing, only works on older Thunderbird versions (52-60).

Current best practice is to use one of the virtual operating systems:
Whonix or Tails, which route all net traffic through Tor, rather than
having to set up per application proxy server settings as TorBirdy does
for Thunderbird.

https://en.wikipedia.org/wiki/Whonix

https://en.wikipedia.org/wiki/Tails_(operating_system)