Thanks for your reply.
I can confirm that all Redstation dedicated servers are restricted to only send mail on port 25 through our premium relay server. You would therefore need to configure your system to send mail through our server.
We provide a free premium relay with dedicated servers, instructions for setup for popular email clients and control panels can be found at
http://www.redstation.com/dedicated_...mailrelay.html
Please follow the instructions provided above if you require to send mail from your dedicated server. Redstation have a policy of not allowing direct or bulk mailing to protect the reputation of our IPs in the interest of our customers.
If you have not already configured your system for our mail relay then this will be the cause of your issues.
Please check your configuration with our FAQ and then test your email functions again.