There are an extraordinarily large number of e-mail messages that "circle the drain forever". They are all spam. They are not all untrue but they are all spam.
I know, I know... you were passing on a useful warning or something important for everyone to know. I still say that these e-mails are spam and should not be passed on.
Why, you ask?
These issues make passing e-mails the least effective manner of disseminating important information.
How should information be passed on?
There are many websites posted by respectable organizations that offer information on the issues found in spam as well as spam and hoaxes themselves. A webpage does not suffer from the problems listed above.
I bet you're wondering what hoaxers get out of sending hoax messages and tampering with 'real' messages.
Some of it is the same urge that leads people to spray paint on walls. Some of it is a bid to collect e-mail addresses. E-mail petitions, which have no legal standing, are often used this way. Even if the originator of the petition is well-meaning once it passes into the hands of a mass mailer a petition may be changed to suit his/her agenda.
Don't pass these messages on!
If you forward these messages you may be compromising the e-mail addresses of your friends and coworkers and spreading disinformation. Instead look it up and if you know them send real information back to the sender in the form of a web address.