IIS 5.0 is installed on windows 2000 web server. The client machines are using windows XP. Request.servervariables("LOGON_USER") gives an empty string on client machines. but this is working on the server. "Anonymous Access" is unchecked. "Integrated Windows Authentication" is checked in IIS.
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: