I am trying to make a custom login page for the hotspot.
How can i create a form for the customers to be able to send an email to administrator?
I mean they would need to be able to send the mail via the html login Page , because they wount be able to use their mail client, in case they didnt buy the hotspot yet.
To the best of my knowledge you cannot do that with login pages hosted on the router itself. Use an external page. At that point there are countless tutorials for any server side scripting languages available via google.
Alternatively allow mail traffic for unauthorized users so they can use their own clients.
I would not open port 25 to unauthorized users unless you do some fancy firewall entries. If a spammer figures out you are open on port 25, you will have a problem.
ADD: Spammer does not need to get behind your hotspot. Only needs one of his spambots (someone’s unprotected personal computer) behind it.
If your PHP/PERL and MySQL programming is up to it, you could try setting up a “personal mailbox” system for your unauthorized users on an Apache web server.