Infrastructure Software

I have sunOS 5.9 running on sun sparc

mail is not working on this system even for local users.
I have tried from the command prompt
mail username
Test email
^D

nothing happens after control D, I don't get command prompt.

I also tried
mail username
Test email
.

nothing happens

sendmail daemon is not running on this system but my understanding is that sendmail is not required. I need mail to work only for local users to receive emails for failed cron jobs etc, it is not required for this system to send or receive emails to/from outside world.

Can someone guide or point in right direction to fix mail functionlality for local users?