notification email not working

[vinmansbrew]

New install of nagios core 4.5.11 on rhel 9.7
I have core set up, it works for almost everything for hosts, a few things don't yet, but that's beside the point, right now.
I have postfix installed, and I can send messages through it.
My issue is getting nagios to send the notification emails.
I have the commands.cfg and contacts.cfg files setup. Permissions on them are nagios:nagios, which is what they are on the old nagios server. (I tried to upgrade rhel on that, and I can get it to 8.10, but nagios plugins break, and I can't get them to resolve.)
I copied over the commands and contacts from the existing nagios core server.

Somewhere between nagios and postfix, there is a break, and I having a problem finding where.

[vinmansbrew]

Well I think I managed to get it. One thing that rhel 9 needs is s-nail, which used to be mailx.
Once I add that, it made whatever link it needed between nagios and postfix.