problem sending mail to domain

The error means what it says - your server cannot find a route to the domain.
That will often mean the problem is with your ISP.

You can confirm that by seeing if you can telnet or tracert to the host listed in the domain's MX records. Lookup the mx records in nslookup on the server...

For example... microsoft.com:

C:\>nslookup
Default Server:  server.domain.co.uk
Address:  192.168.1.1

> set type=mx
> microsoft.com
Server:  server.domain.co.uk
Address:  192.168.1.1

Non-authoritative answer:

microsoft.com   MX preference = 10, mail exchanger = mailc.microsoft.com
microsoft.com   MX preference = 10, mail exchanger = maila.microsoft.com
microsoft.com   MX preference = 10, mail exchanger = mailb.microsoft.com

maila.microsoft.com     internet address = 131.107.1.7
maila.microsoft.com     internet address = 131.107.1.6
mailb.microsoft.com     internet address = 131.107.3.123
mailb.microsoft.com     internet address = 205.248.102.77
mailc.microsoft.com     internet address = 205.248.102.78
mailc.microsoft.com     internet address = 205.248.102.79
>

When you have the MX server information, see if you can telnet to port 25 of the remote server.

For example (using the above information)
telnet maila.microsoft.com 25

If you get the route issue, do a tracert, so using the above example

tracert maila.microsoft.com

If there is a route issue the traffic will die at some point - when you will need to speak to your ISP.

Simon.

no matter what domain i try I get connection failed when trying to telnet.  I am using the command:

Telnet mail.domain.com 25

and still getting connection failed.  what am I doing wrong?