This regex is in essence the same with the one above, except that it allows any non-ASCII UTF8 characters in any part of an email address. We still need to actually send the email to know its existence.
PS: A valid email address does not necessarily be an email address that exists.
When the user presses Enter, than Java Script checks that email address is valid or not.
If the number is valid then alert message will be displayed as ‘Email address is valid’.
With the extension of SMTP by RFC6531, Unicode is allowed to be part of email addresses.
While the code part is in ASP, the important part is at the top, which deals with email validation using Java Script.
ASP/Jscript Email Validation For a nice listing of regex patterns, visit Regex
Webapps often ask users to input email addresses for authentication or referrals.
To provide good experiences, it is always a good idea to validate email addresses before actually using it, such as to check for typo in UI to give immediate feedback or to verify the validity email address before actually sending the email. If we follow the definition in RFCs (RFC5322 and its references), it will be overly complicated.