The dial by name spelling can be changed from the individual's mailbox.
From the main menu, they need to enter Setup Options (when prompted)
Then enter Personal Options
The system will ask if you would like to change your spelled name. Press 1 for yes, then follow the prompts to change the spelled name.
BTW, do you have softkey access and if so, are you a System Manager (you would see MORE as the last softkey on the right and then if you press MORE, you would see MGR on the second softkey on the left)?
Only someone designated as a System Manager can change the system Greetings on a NEAXMail/Elitemail.