Lesson in economics - just because you don't pay for it yourself, doesn't mean there is no incremental cost. Bandwidth costs money, and somebody pays for it, somehow. Yes, it gets cheaper all the time, as new technology allows more and faster to be pushed down the pipe, but then it's used more all the time as users take advantage of the increased possibilities. Just like computers, phones, etc. For downloading, most users have unlimited usage at their bandwidth. Some have to choose limited usage plans, like P.K. Mine is $100/month ADSL, supposedly unlimited and a certain speed, but the more users they put on, the slower it gets.
Then there is the issue of bandwidth bottleneck from hosting server to backbone, which can happen when site is busy. You'll see when storm season begins...
This is straying off course a bit (as she drags the soapbox from under the stair), but everyone using email and the web should know this.
The truth is, our bandwidth costs, however small they might be, would probably be 1/2 what they are, if SPAM'ers could be hunted down and put out of business for good. With many thousand sending out several million mails/day, the estimates of internet bandwidth used for "junk" are very high. (Not to mention admin costs for security layers, etc. eventually paid by the user.)
As soon as my email host software (IceWarp) gets upgraded to refuse IP Blocks via wildcards (i.e. 220.*.*.*), I will stop everything in Asia, and much of Europe, from even being accepted by my mail server. (They keep saying they can do it in the last couple of releases, but it doesn't work.) I don't know anyone in these place, so I don't need to get email from there.
I research and report a lot of spam, been doing it since mid-90's. I don't care who mailed it to me (which could be forged or relayed via an innocent party with poor security), I just go after what they are trying to sell - the website in question. I've successfully shut down many domains being advertised via SPAM. But, the mail hosting providers and domain allocators in Asia, and some other places, are so poorly regulated, that reporting to them just gets your address on another bunch of mailing list CD's for sale.
And, they've only scratched the surface. There is so much money to be made, that people want to 'take it and run', not waste time and money to set up an infrastructure of regulations and consequences and agreements with multiple jurisdictions, etc. So, they don't care if their customers are eating up the Western Hemisphere's bandwidth, etc.
A large % of "send this to everyone you know"-type emails are designed to support this industry, by collecting more email addresses. Please discourage this type of traffic, by deleting it instead of participating, and by asking your friends to do the same.