Unable to send buddy invitations

I'm a newbie and don't have much knowledge on web designing. With a much hardship I have built a test website and hosted it on www.kilu.de for live tests. The issue is that whenever I send an invitation to a valid email address (I used my test email account for this purpose), it shows "Your invitation has been successfully sent. You will be notified when the invitee joins the site." but when I check the mail inbox, I don't receive any kind of invitation email. I have no idea what i should do to rectify this.

also whenever i try to create a new user account, providing a unique username and valid email address, it shows "Your password and further instructions have been sent to your e-mail address." But no email is received by the user. Being a newbie I have no knowledge how to make it work. I shall be grateful to all guys for your sincere help. Thanking you, Raidang.