(Very) Simple Mailing List Form?

Hi there,

I’m working on a site for my business and I would like to include a form (1 input text, 1 submit) that allows people to subscribe to a mailing list. The control would exhibit the following behavior:

• Unsubscribed users would see the text field & submit button
• When the user clicks submit:
• A validation check is made against a regular expression
• A check is made against an “mailing_list” table in the database to check for duplicates
• The email address is inserted into the table
• The system will attempt to add a cookie which shows that the user is subscribed
• If the system detects the cookie then the form is hidden and a message is displayed

I’m pretty new to PHP but I’ve been writing .NET for a few years and various other languages before/during. I suppose my questions are:

• Does something like this already exist?
• If not can I write this using regular PHP or will WordPress get upset if I start doing postbacks (etc.) outside of it’s control
• If I need to code this around WordPress then I guess I’d need to write this as a plugin – is that right?

Thanks for your time,

Olly