I also have not had to touch the config in years and running in proxy mode (just using it for spam filtering) So was surpised when it also was not working. I am using cloudflare and a number of other devices and softwar items outside of xeams, so possible something changed up ahead of the proxy or on the smtp server (I've not changed anything outside of patching of devices firmwares, os patchs, etc)

Looks like I will need to change my setup anyways as I as told proxy will be deprecate in a later version. hope that holds off until I can get migrated my VMs to RHEL8 and containerize everything.