Somebody asked me a similar question the other day.

According to https://en.bitcoin.it/wiki/Using_Bitcoin, the "Client will refuse to send payment to a misspecified address."

There is a checksum in place to ensure the address is valid, so you are unable to send to an invalid address.

Hi everyone,

I've been interested in Bitcoin for over a year now. With recent events, I've been getting much more interested in everything about them. I bought in early, but ending up spending most of my coins.  I was kicking myself at first, but that's the nature of the beast, and I can't dwell on "how rich I could have been"...

Anyway, I've lurked on these forums for a long time, and finally want to be part of the community.