The unexpected email
In almost every discussion of “how to stop spam” someone will come up with the idea that if a recipient only allowed known people to send them email then the spam problem would be solved. There are lots of problems with this type of solution, but one of the biggest is that it ignores that sometimes the unexpected email is wanted. Typically, these unexpected but wanted emails is from an old friend or contact. But sometimes, the unexpected email can actually look like unsolicited bulk email and yet be wanted.
I actually received one of those emails today. The folks at http://schmap.com found my flickr stream and sent me email asking me for permission to use a couple of my photos in their London city guide. Completely unexpected, but very welcome email.
Sometimes, in the struggle to keep email useful and to keep spam out of the inbox, we forget how useful and wanted that unexpected email can be.