We have checked our DNS entries and it looks all OK, we have used the original email string provided by Marketo, but now all our links are 404. Please fix this asap as it is very inconvenient, urgent and pending with support for a while.
Pleas post a screenshot of your Admin » Landing Pages setup. This won't be possible for the Community to look into without real data.
Are you sure the DNS has the right link from Admin?
Did you make a change recently?
Are you sure you put the CNAME into the Admin area correctly?
Do you have any active pages we could check?