I recently removed about 600 'thin' pages from my site which are now showing as 404 errors in WMT as expected. As I understand it I should just let these pages 404 and eventually they'll be dropped from the index. There are no inbound links pointing at them so I don't need to 301 them. They keep appearing in WMT as 404's though so should I just 'mark as fixed' until they stop appearing? Is there any other action I need to take?

Thanks for your reply. I makes sense to me to have users land on a mobile page but just to clarify I'd be redirecting mobile traffic to a completely different domain not just a different URL. Will that be a problem?

I'm working on a site that has lots of great content and ranks well but essentially the money is generated by affiliate links. I don't have a mobile version of the site but the company I'm affiliated with does offer a mobile redirect to their domain. Will redirecting mobile traffic to a different url hurt my SEO? I think the user will get a better experience by landing on a mobile page but I don't know if google will see it like that.

Any thoughts?