Is sendmail running? Try the following
ps -Alf | grep sendmail
where > is the command prompt. This will show all running processes and then grep (search) the output for the word sendmail. You should get three entries with the following at the far right of each
sendmail: accepting connections //Recieving mail which is comming in
sendmail: Queue runner@..... //This is the daemon which actually sends mail
grep sendmail // this is just your grep for sendmail
If it is not running you'll have to start it up but let's take things one step at a time (read: I can't remember if you have to do anything special, I'm just going to go and check :/)
HTH
Bubble