It doesn't make sense that it wouldn't get through with just those email addresses in the body. It is definitely still getting sent, so the only possible issue would be spam blocking somehow. Are you sure it isn't in a spam folder? Have you tried sending TO a different address and see if it comes through? When the emails do work, do they come with the correct FROM and TO?
Have you tried not setting the smtp server and using the default one? It looks like the sample mail code from fasthosts uses the extra parameters for setting the from. You might try checking that setting and leaving the email server blank.