Notification emails

Hi All, I have recently changed the url of my forum to a domain name that I already owned. Everything is working ok apart from some of the links sent out in email notifications i.e. notifications of replies to posts
and new user email activations.

In some cases, like removing a test account, I get an email saying my account has been removed with a link back to my forum. The link will be (made up link) http://www.myforum.co.uk/other stuff. Clicking this link goes to the appropriate forum page as it should.

However on topic replies the link in the notification email, which will be like: http://myforum.co.uk/other stuff, does not link back to the forum instead it links back to my domain name provider.

If the link sent by my forum has www. in the url it works if it does not it doesn't work.

Hope this makes sense to someone!!!! It's driving me nuts!!