My ActionMailer scripts look perfectly fine. However when I try to send from the console I get the error.I'm on Ubuntu 10.04. Any ideas would be helpful.

command not found: /usr/sbin/sendmail -i -t

This is probably because you don't have a MTA installed. You could look at using something like ssmtp to just deliver your mail to a real mailer that can queue your outbound mail.

Be warned that this program will not queue mail in the case of a network failure, it needs to be able to deliver mail in all circumstances. If this solves the problem then consider installing something more heavyweight such as qmail or postfix.

If you already have a MTA installed then check for it in /usr/lib/sendmail, if it's there then simply symlink it with:

ln -s /usr/lib/sendmail /usr/sbin