You were probably sent here by a friend or loved one. Also, chances are you recently included said friend in a mass email sent to many people. This friend would like you to learn the proper technique for sending these types of messages.

First, the golden rule of sending an email to more than, say, 15 people at one time.

Don't Do It. Seriously. Don't.

Now, if you must, here's how you can do it and still maintain the friendship and respect of the one who sent you here:

After you have selected the throngs of names to which you'll be forwarding the video of the cat playing Chopsticks, you'll probably have a very long list of names in the 'To' field of your email program. Complete the following steps:

Why is it a good idea?

Well, I'm glad you asked. Some people (including the guy typing this right now) are somewhat particular about who gets their email address. While we don't consider it a state secret or anything, we also don't want people just handing it out willy-nilly to any Tom, Dick or Harry on the Internet.

Using the BCC field allows you to send your email to as many people as you like without also giving each address to everybody on the list. You see, once people see an email address that has received an email about cute cuddly things, they tend to assume that said person likes receiving those types of messages. Sometimes, this is true, but sometimes it isn't.

When you send your message and utilize the BCC field, you're respecting the privacy of each individual recipient. This is a good thing.

For more information on the BCC field, read this.

So, do your friend a solid - use BCC from now on.