vBulletin Mailing Problem: Only for People with vBulletin knowledge

Hello, I have a forum called [login to view URL] which runs on vBulletin version 4.2. The problem is with mail sending. Whenever someone registers, it sends email verification to Gmail Account but not on Hotmail account. Also, it is not sending me mails in my Admin Email ID whenever someone sends a message. The Admin email ID is a Gmail ID. I have used the vBulletin Diagnostics to send test mails. I do get test mails in my Gmail ID but not in Hotmail ID. I have tried with both -f enabled and disabled. But still my Hotmail account does not receive any email from my forum. Hotmail account does not receive mails- neither on user registration nor on Diagnostics test. The diagnostic test report does not give any Error. I am using a Shared Linux hosting of GoDaddy. So, I need help in two sections- 1. Receiving mails in Hotmail IDs get resolved. 2. The Contact us section sends mail to my Admin ID which is in Gmail ID. I have tried internet tutorials etc but with no luck. Please help me out.