and also nas_connecthome or connect home if you are doing email home

if on 5.6.39 and > ..is it not in Support > Email User ?

try /etc/mail/sendmail.cf

yes, Celerra Manager -> Support -> Connect Home and EMail user tab is also worth checking

I dont think they use sendmail.cf

Well, I see those tabs, but there is nothing populated in it. Our SMTP servers are changing and those admins want us to change them to the new names.

Are there initial configuration steps of a Celerra where you'd enter this that would not be popluated in the GUI?

Better yet, is there a CLI command to run that will allow me to view what it is currently set for?

well - is your Celerra actually able to send EMail right now ?
just try Mail -v and see which mailserver it connects to

If yes then check if the "smart relay" line in sendmail.cf was configured - default its emtpy and just contains DS

for "Email home" check /nas/sbin/nas_connecthome -info