Not receiving e-mail for activity in my blog

Hello,

I am facing a strange issue here. I have provided my email ID in Wp options panel and I am not receiving any e-mail about my blog activity like new user registration or comment moderation. Also Contcat form submission mail,s are not coming to my specified email address. It was working fine before I changed my hosting service. Now I am not sure where to make the changes to make it work.

Please help me regarding this.