Well, this basically needs you having access to the web server configuration - or your ISP doing that for you.
When configuring web server, you have the option of setting up users and groups, and access
Any business that wants to seriously grow needs to keep the needs and desires of an international audience of their websites in mind. Making a website friendly to international users isn’t prohibitively expensive and can provide an incredible return…
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions.
Consider email address RFCs:
Look at HTML5 form input element (with type=email) regex pattern: