Utl_smtp

I need to develop a package, that should trigger a mail to the mail id entered by user at runtime. How cani do this using utl_smtp package.

The form i developed has  a text box that is used to capture the email address at runtime from the user. The mail id can be anything( gmail, ymail,or company mail id). As soon as the user clicks the submit button the oracle package should send the mail. To implement this requirement how to configure my utl_smtp package.

Do i need the host and port number of Gmail, Ymail......