The microsoft URLEncode method ignores the documentation in RFC1738 which states that:
".... the special characters "$-_.+!*'(),", and reserved characters used for their reserved purposes may be used unencoded within a URL"
So for example, [email protected] becomes myaddress%40mydomain%2Ecom, whereas php and other languages would encode this as myaddress%40mydomain.com
This can be an issue when porting from asp or if you are doing string comparison of strings urlencoded on different platforms.
NB. php will correctly decode myaddress%40mydomain%2Ecom to [email protected], it is only the encoding that differs