CmdrTaco from the its-for-your-own-good dept.
Jamie ran across a story about censorship on MSN. Essentially, a number of suspicious strings result in silent failure of delivery. The strings are unsurprisingly things like .scr and .info. They've started maintaining a list if you're interested. Personally, I'd rather they fix the vulnerabilities that make those strings dangerous in the first place: it's not like IM is the only place a URL can get on your machine.