How do you find out your Exchange ActiveSync server name?

If it is for your client side setting, put in mail.yourexternaldomain.com which points to your public ip address / firewall from where the request gets forwarded to your exchange server.

If you have a frontend/backend scenario, the frontend server will be responsible for activesync functionality.

This is the situation. A client is setting up his iPhone to retrieve his company email. I've given him the information I've used to setup MANY Palm's in our organization (all of which connect perfectly), but he isn't connecting. Of the information he tells me he needs to input (username, password and server name) I can verify all except the ActiveSync server name. Where is this listed on the Exchange server? How do I verify the server name I've given him (whicjh has worked and continues to work, for all the Palms in our organization) is the correct name?

What is the server name for your Windows Palms?
 Version of your exchange?

The server name is webmail.companyname.us.
Exchange is 2003.

You have said that the affected user is from another company, try to get information about how he actually tries to get into webmail.
Then tell me what you get when you try to browse from your machine: "https://webmailurl/microsoft-server-activesync"

He isn't from another company. He is from our company.
I get "Internet Explorer cannot display the webpage".

Kindly check the user credential by accessing and testing the activesync test www.testexchangeconnectivity.com

It is failing because it's attempting to use port 443. We just use port 80.

443 has to be open for mobile access. That is the default behaviour and is secure too.

Not if you chose not to use SSL. Then the default port is 80, which we use. Like I said, I've been connecting all of our PALM Treo's this way. Eventually this will be reconfigured.
So I'm assuming there is no where I can verify the address for the Activesync server.

Try configuring the affected user's Activesync profile on one of the PALM Treo.

Also find below the links which explains as how to go about with iPhone for assistance.
http://support.kerio.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=489
http://www.chemlab.org/2008/12/08/configure-exchange-2007-apple-iphone

There is a an option on the iPhone to turn SSL off. This might be your problem...
It is available under Mail => Mail, contacts and Calendar =>Account Name => Account Info.
The reason it is hidden is that it is certainly not recommended. All PWDs are send across the internet in clear text.