I get a lot of emails every day (600-700 on a typical work day not counting spam) and can tell you that while I read all emails, those people who waste my time with their emails, tend to get future emails delayed or ignored.
As an example, the people who copy me unnecessarily on emails (they think it’s better to copy everyone than to take the time to really think who should be copied) end up sending me emails that I have no need to see. When I receive a few like that from an individual, future emails from this individual would tend to not be read right away because I just assume they aren’t going to apply to me anyway. Those people who are careful and only send me emails that apply to me, don’t have this happen so I read and address those as soon as possible.
Needless to say, this would also apply to people who forward jokes and other “funny” emails.
If someone sends me an incomplete email (for example, wanting something but not giving specific explanations of what they want) end up wasting my time and theirs. Rather than sending one complete and specific email, they send an email, I have to reply asking for more information then they have to reply with the requested additional information that was requested. If the initial email had been specific, much time and effort could be saved. As an example, if someone wants some content changed on a web site I have created, they should send the specific URL of the page that needs to be changed (just because they know where they are referring to doesn’t mean I do) and also send the specific content. In this particular case, sending too much information is better than sending too little. If there is a specific spot on a page that needs to be changed, sending a graphic pointing out the spot is extremely helpful (Snag It is great for this).
Since email is easy to send and inexpensive (for most people, free) people tend to take it for granted. However, if it’s used in a business setting, it should be treated just as professionally as all other forms of communication.
Have a great day!