Spam in the workplace

In comments on my last post Lux says:

It seems to me that in regard to PR people sending press releases to a professional journalist, you’ve got a very specific use case with slightly different rules of engagement from the norm.

I think that is a valid point and that some people, because of their job, will receive mail they do not want or have not asked for. I also think that the business has the ability to tell the employee that they cannot block the mail.
That being said, I think senders have an obligation to determine who is the right target for their unsolicited email. Just randomly sending offers to sell stock photos to the editor at wired might be the right thing to do, but there might also be a better target. By sending unsolicited email you are asking someone for their time, and you should be respectful of that time. Respecting the recipients time may mean you send out less volume in the long run, and may be more work for you as a sender, but that is just a cost of doing business.
This all goes back to my contention that relevancy is the key to good success from email.