Today I learned that Forte also provides Usenet access. Well, it makes
sense. Although based on the headers, maybe they route through
EasyNews?
(You should be able to to use Forte Agent regardless of your NNTP
provider... unless Forte turned evil and made the software
subscription based too. But I don't see any evidence of that on their
website. Just change the host name in settings to point to the new
news-server. Personally, I like spinning up a new .rc file when I do
that in case of numbering differences, but it may not be necessary).
As for Usenet providers, they're getting thin on the ground... and too
many of them are focused on offering binaries. How well they do with
spam, I don't know; I can't imagine they care very much... especially
the binary-focused ones. From what I can tell, they're mostly
back-ends for NZB search engines so the spam never gets seen
Still, many of the services offer free trials so you could just sign
up and see for yourself. Eweka
https://www.eweka.nl/en , TweakNews
https://www.tweaknews.eu/ , Newshost
https://www.newshosting.com/ and
Usenet.Farm
https://www.newshosting.com/ all let you try for free.
Create an account, configure a free NNTP client with their newsgroup
settings, and refresh daily to see how they compare to one another
regarding spam.
There's also good ol' Eternal September
https://www.eternal-september.org/ which apparently /is/ trying to
fight against the spam (not surprisingly, since its text-oriented) but
given its limited resources its apparently having a bit of an issue
keeping up.