Applied on: Windows (ASP) hosting plan
In websitepanel when you create an email account for a domain, a "mail domain" created automatically by control panel. This mail domain creation will be an added node in hMail server (your SMTP mail server) responsible to manage your email accounts, alias, mailing list and associated configuration.
You cannot have any email address or alias without it. So at other hand you cannot delete a mail domain if you have an email account or alias for that mail domain. Nor you will be able to remove a domain, if you have email addresses for it.
Once you have a mail-domain, you can configure three things directly by using mail-domain link as stated below;
1. You can add Email Domain Pointer (Alias) for that mail-domain so one email mailbox can represent with more than one domain without actually creating the second email address
2. A catch-all email account setup can create here so any email sent to non-exist email account, can pick up at other email address
3. DomainKey Identified Mail DKIM configuration so any email sent with your domain's signature.
This mail-domain is important in your advance level mail server requirement. You need to understand its effect.