I just installed a default install on CentOS 5.6, and I needed to use an external server to send email, as I do not have a dedicated IP. I had tried using sendmail, but the few tutorials I tried didn’t work well. So I asked Mr. Google and I found this site:
If you don’t have Postfix installed, or any of the other required libraries they mention, you can do the following
yum install postfix yum install xmlsec1-openssl openssl openssl-perl openssl-devel openssl097a yum install cyrus-sasl cyrus-sasl-lib cyrus-sasl-plain cyrus-sasl-md5
Obviously change your config files to match your account info, but it works like a champ. I hope this helps others.
A Second Example
Today I needed to do the same thing on a CentOS 5.7 (Final) server, and found the following to work great! I used it with my mail settings, but should work for anyone. I did have to use the TLS options, so if you’re like me, be sure to follow those, as well.