In my development PC I want to see all mail sent using PHP
mail() function. Is there any dummy mail server that could show all sent mail (regardless of their recipient) and collect them in a mail box to preview?
Here you go: smtp4dev
phi's solution is great if you have a Windows environment.
If you have a Linux environment - then you can setup postfix to deliver all email to a local mailbox.
Here is a link to get you started - http://serverfault.com/questions/144325/how-to-redirect-all-postfix-emails-to-one-external-email-address