domain name does not open the website, redirects to default IP instead of opening www

Question

I recently changed NS of one domain to another host and created a domain using Helm Control Panel.

The problem is that when I type domain name (ie. www.MyDomain.com) instead of opening the coresponding website, it opens host webmail page which is served by smarter mail.

I have cleared dns cache, rebuilt and updated it. also I removed the domain and added it again.

Pinging the domain name returns server's IP address and it's up. The hosting OS is windows server 2003.

I appreciate any comments to solve the problem.

Edit 1:

Though this was a long last headache, I solved the problem by removing domain's DNS entry alongside with all alias domains attached to it directly in DNS Server console, restarting server and then rebuilding DNS Zone via Helm Control Panel. I'm not sure if this was the best practice but it seems there was a mix of domain's DNS, alias domains' DNS, Hosting software, Caching problems.

Edit 2:

Actually this error was not about the DNS stuff, it is a failure of Helm Control Panel adding/removing alias domains. To share the experience, I Add a answer to this question.

Answer 1

This was not a DNS error.

I found the answer when examining IIS where i noticed the website was stopped.

Forcing the website to start, this error message poped up:

IIS was unable to start the site, another site may already be using the port you configured for this site.

Further investigation revealed that one same domain alias has previously added to another domain/host.

Removing this alias from IIS > Website Properties > Website > Advanced > Advanced Website Identification, fixed the problem.

What led me to assume a dns problem mistakenly was that default IP of server is set to mail server by default. so, when a website is stopped the domain points to mail server.

Hope this help for future.