No need, my IT already do this by running the MimeCast email filter [1]. Links to non-whitelist sites are expressed in the format:

    https://url.uk.m.mimecastprotect.com/s/<random_string>?domain=<domain_name>

Maybe I can tell the link is from Google, but not what is likely to be in the URL. It's a complete surprise as to whether I will be looking at a web page or downloading something.

[1] https://www.mimecast.com/