Official URL: http://www.maths.tcd.ie/pub/ims/bull53/R5301.pdf

Let (X,p) and (Y,σ) be metric spaces. A function f : X → Y is (by definition) bounded if the image of f has finite σ-diameter. It is well-known that if X is compact then each continuous f : X → Y is bounded. Special circumstances may conspire to force all continuous f : X → Y to be bounded, without Y being compact. For instance, if Y is bounded, then that is enough. It is also enough that X beconnected and that each connected component of Y be bounded. But if we ask that all continuous functions f : X → Y , for arbitrary Y, be bounded, then this requires that X be compact. What about uniformly-continuous maps? Which X have the property that each uniformly-continuous map from X into any other metric space must be bounded?