IM/instant message filters needed

I would like to see more filters on who can IM me. I've started to see IMs (unsolicited commercial messages) from people I don't know and have never met.

Possibly a good start would be two checkboxes: one for IMs allowed from friends, and another for IMs to allow people whom I've messaged. A more complex but desirable option is to also allow messages from people who are in my location. A final option, maybe a meta-control over the above, would be to allow IMs from anyone (even if they don't pass the above filters), but only while I'm logged in.

These measures would stop the IM-to-e-mail spam created like the following e-mailed IM I got today when I was logged off:

"[4:38] bagaqunfa Aeon: Dear Secondlife Residents,Welcome to http://www.tradelinden.com .There is a large amount of lindens here and the price is the lowest of all.Besides,we have a lot of promotion measures.The more lindens you buy,the more bonus you can get. SO,why donot you come and have a look? DO NOT lose such a good chance! Have a Great Day!!"

Or the four I got for a camping-bot-client.

Mute the person sending you the spam. Problem solved

Alls well when its the same person. The four IMs I got I got from four different people to my four different alts.

And besides, I'd have to log in to mute them.

These spammers can create a free account and on the same day spam with it. Muting such people does nothing but fill up the mute database and make SL slower for everyone by processing mute records created by hundreds of thousands of residents all muting the same series of one-use accounts.