Exchange 2000 SMTP Global Settings

This sounds like a relay problem on the exchange server. By default, Exchange doesn't allow any relaying to occur (which is a good thing!) So you have to specifically allow any traffic to relay.
You can edit your relaying properties by opening up Exchange System Manager, double click your domain, double click Servers, double click your server name, double click SMTP, right click Default SMTP Virtual Server, click on properties, click on the Access tab, click on the Relay button, and add eitheran IP Range to allow relaying (the ip range of your local network) or your domain name.
Hope it helps!

Hi,
you have an logical Problem rather then an relay Problem. Change your SMTP Domain Settings on the SMTP default Virtual Server from mydomain.com to a *. So your Exchange server is responsible for delevering e-mail for all e-Mail organisations rahter then your own Maildomain. Configure Mail delevery for a "smartHost" on the Configtabs on your SMTP Default Virtual Server, so all Internet-Mails will be routed to the SMTP Server of your ISP. If youre ISPs doesn't supports EHLO you should configure an SMTP Routing Connector for Internet Mail delivery. On this Connector you can turn of Ehlo and force youre E2k Server to communicate simple HELO. This is, depending on your current Internet connection type, better cause you could configure the amount and the connection Times to the Internet very smooth and clearly.

Regards

Frobo

Answer One wrong
Answer Two wrong

Been there, done that.

You have to explicitly tell Exchange to accept email for users@mycompany.com, and you also have to tell exchange to create address for existing users@mycompany.com.

In Exchange Systems Manager. Recipients --> Recipients Policy. Double click default policy on right pane. Properties are displayed. Go to the "Email Addresses(policy)" tab. Select New, SMTP, in address field put @mycompany.com. click ok, select the new @mycompany address, set as primary, Your Done. It will give each user an address@mycompany.com, and your exchange server will recieve the message. Give it atleast 15 minutes to propogate thru AD.