Horde on CentOS 5: Can't send outbound message?
 

My setup is local install so I don't expect it to receive emails from the internet. However I do expect it to be able send messages to the internet, but it doesn't seem like it. I have tried setting up on FreeBSD before and it was able to do so but I wasn't involved in the setting of the machine though. I was just tasked to setup Horde... Any insights please????

What are you using to check that the email has been sent? Do you own a domain, and are you using it? Some email servers, e.g., hotmail, gmail etc., will not allow mail from a dynamic IP address to be processed on their servers.

Sorry this might be the stupidest question I have ever asked.. My IP is provided to me by my ISP thru DHCP. No I don't own a domain. Could these two things be the reason I can't send? Basically I am just using my IP as my domain...

It probably is working from your end, but what happens is two fold: your ISP has probably blocked the common email ports, such as port 25 for SMTP, and others like 110 for POP etc. The one you want is port 25 I would think. The other thing is that most mail servers will not accept mail from dynamic IP addresses, so even if you buy a domain, or use a free one, most email servers won't accept your mail. I've done this type of thing before, and hit the problem of not being able to send mail past my router, because of blocked ports. No easy answer, the only way to test is if you've got a proper, internet facing mail server that you can play with. I did!