This module tries to solve the valid email problem by checking that the address really exists when it is entered by the user. First, it checks if the domain/host part exists at all, and reports an error if it does not. Then, it tries to validate the user name too, by sending a HELO/MAIL FROM/RCPT TO chain of commands to the SMTP servers for the found host.
- Unpack in your modules folder (usually /sites/all/modules/) and enable under Administer > Site Building > Modules.
· Drupal 4.7.x/5.x