What would happen if another website linked to you, but made a mistake in the link, and ended up sending people to a page which doesn’t exist? It would be a terrible waste, but would you even know? I’d suggest the best way to tackle this is firstly to track down any existing broken links and fix them; then set up a way to monitor them in the future.
Tracking down any existing external links which don’t work is pretty straightforward if you have our old friend Google Webmaster Tools installed. You’ll find it under “Diagnostics > Crawl Errors”. Some analytics or weblog applications can also return this information. Once you’ve got a list, you’ll be able to see where the links are coming from. Most will probably be internal ones, which you can fix easily enough, but if there are external ones, the first thing I’d try to do is to contact the siteowner of the linking site and see if they’ll make the correction. Be sure to send them details of the page on their site which needs amending, the link which is not working, and the correct URL they need. Most webmasters don’t like their site to have broken links, and will happily amend things.
The other approach, and one which you might be forced to adopt if the external site won’t help out, is to set up a “301 redirect” from the incorrect URL to the correct one. This should work fine, but you don’t want to set up any more of these than you have to, so try contacting the other website if you can.
Tomorrow I’ll look at how to monitor bad incoming links.