I need a way to send mail from Linux to our own staff. The mail load is about 2-3 emails/day and they will never be replied to. For example, the output from an rsync operation needs to be emailed to an administrator so they can see that the remote backup ran.

I was going to use sendmail but all the docs I've come across tell you how to set it up for a full-blown server where you have a domain and everything. I can use a remote SMTP server that we have. If I send from localhost it gets rejected. How do i send emails from the CentOS 4.1 server using our ISP's SMTP server?

TIA
caleb

sendmail is designed to run large-volume servers. You might consider using another MTA such as qmail or procmail. Personally, I use qmail for my own email and find it very easy to configure.

For sending email from scripts via a remote SMTP server, you might like to look at using Perl modules like Net::SMTP or Mail::Internet.