I often use http://www.tinyurl.com/ to shorten the URLs of external sites linked
to from Wikipedia. This is useful for stopping the diffs from being too wide to
However, tinyurl.com and other link-shortening services have just been added to
Wikipedia's spam blacklist. Of course, it can't be helped that some people will
try to use it to bypass Wikipedia's spam filter in order to link to bad sites
(pornography, malware, etc.). However, it's quite straightforward to stop this
abuse of these services, short of banning links to URL redirectors altogether.
When a link to a URL redirection domain is entered into a page, MediaWiki should
follow the link to find out what it redirects to. If the destination of the
redirect is on the blacklist, then veto the link. If it isn't, then allow it.
Following every link to see if it redirects somewhere might put more load on the
server than is desirable and slow down the process of saving a wiki page.
Therefore we probably should have, as well as a blacklist, a 'redirect list' of
domains in which to follow redirects.