If the user register, the confirmation mail goes to spam folder. After doing some R&D, I enabled "Use two e-mail fields on registration form > Set password" and tested; it goes to inbox from the web server. But as i badly need to show the demo to my supervisor from my local server instead of live, using "Acquia Dev Desktop", it goes to the spam folder. How can I prevent the message from going to the spam filter?
You should use the SMTP Authentication Support module: http://drupal.org/project/smtp for sending email messages. You can go there: https://stackoverflow.com/questions/8939238/gmail-smtp-configuration-for-drupal-7 to see how they can use the SMTP Authentication Support module with Google Account.