Secure Notes helps solve the problem of exchanging sensitive information with people who do not have the same tool-set or skill-set. It provides a system, similar to password reset links in which a one-time node creation link can be sent to a person's email address. This is meant to solve the problem of exchanging sensitive passwords via email.
DrupalSecure Code Sniffer (secure_cs) is a secure coding validation tool for Drupal built on PHP_CodeSniffer and modeled after work on DrupalCS in the Coder module.
Are you looking for a way to specify a no-reply email address for all mail coming from your Drupal site without having to muck around with the MTA configuration on your server?
Regcheck is a super lightweight and simple module that adds a hidden checkbox on the user registration form, and kills the registration process if it is checked.