Does WP has such plugin to send information to users by email after they submit their email address? an instant delivery by mail, specific to a certain post.
I use Feedburner for tihs. It will give you the code to insert into your blog so when people sign up they will get a daily, weekly, monthly or whenever you decide email with all of the new information on your site. It's very customizable, and I like to use it for my regular RSS feed too. Maybe it will work for your purposes. www.feedburner.com Come to think of it, I think there's an official Feedburner WP Plug In...check the Feedburner website for a download.
Yes but i'm looking for something diffrent, i need users to opt-in so that i can send them a specific information and not daily information and it also needs to be send instantly. for example: opt-in to recive a file by email or opt-in to receive a report.
Yes there is a WP email plugin that I use specifically for this purpose. Check this out: http://www.justinshattuck.com/comment-relish/
You could use a GetResponse or Aweber opt-in form and give away a free report. Or combine the Feedsmith plugin with Feedburner. Every time you post, an email is automatically sent to your subscribers to let them know.
Wounded- what you're after is email marketing software- this will generate code to place on your thankyou page (I don't know of any programs/services that have a wordpress plugin to do this). I've used Aweber, 1-2-all's script and Interspire Email Marketer (the best in my opinion) They're not cheap, but with email marketing there's no such thing as a free lunch. Hope this helps.
I guess i will have to develop my own! since i'm running an advertising company and will need that for my clients