Gail, It's not "Just You." I just scanned through my last couple of years of newsletters from farsight.
Courtney / Farsight should be alerted to this. Also should check with their support person at Mad Mimi (madmimi.com ) / GoDaddy for assistance.
I'm not sure what prompted the change, but on 16Nov2020, Farsight newsletters started using [email protected] in the "from" in the newsletter software. That is causing a "domain authentication failure." which is one factor which email servers use to decide how "spammy" emails look.
Each email provider chooses how they will treat authentication failures. Some simply tag them as "potential spam", some flag them with a warning. Some allow the user to change settings on what to do with suspicious emails themselves. ... Yahoo, is apparently deleting them, where they may not have been before.
I've not had any problems receiving farsight newsletters on my proton mail account. They do display a red banner alert warning about the authentication failure, when you open a farsight newsletter. If you are looking for a reliable free email provider, you may wish to try ProtonMail. They are located in Switzerland. Here is their signup link: https://account.protonmail.com/signup
The free version does not have as many bells and whistles, but most people will not care. If you do not want to have to give them your cell phone number, then do not sign up while on a VPN, or through TOR -- otherwise they will more than likely want to send an SMS message to your phone.
Caveats with ProtonMail: The username you choose cannot be changed. When you login you will need your UserName and Password, as usual, but then you will also have an "Encryption Key" Do not lose it. Your emails will be encrypted (except for subject line), and able to use PGP encryption when you send sensitive information. The encryption key is necessary for you to be able to read your emails. You can change your encryption key; however any emails saved with a different key will not be able to be read. They also have a setting which allows you to use the "beta version," which I do not recommend you doing unless you are using an "extra account," in case something goes wonky with their test software.