Please don't put my email address in the To or CC fields of messages being sent to people I don't know!Please protect email addresses as you would phone numbers -- unlisted phone numbers.
BCC stands for "Blind Carbon Copy." Historically, it would indicate who had received (or should receive) a copy of a memo without being listed in the "To" or "CC" fields. In the context of email, it indicates who should receive a copy of the email without being listed in the headers. If you're sending email to a number of people who do not (or should not) know each other, it is courteous to conceal their email addresses by using BCC.
Many people are protective of their email addresses. They don't care to receive email from random people on the net. Perhaps you've decided your clever joke, worthy cause, or business announcement was worth sending to them. You've also sent their email address to everyone else on the mailing.
Look at it another way, would you send your entire holiday card list out with each card you sent? Of course, some people would not like getting the list and others would not appreciate being on the list being sent everyone.
And if you're in business, would you think of giving away your contact list? That's what you're doing by including everyone in the To or CC fields. And some recipients of your mailing might consider everyone else on your list interested in similar mailings and feel free to use the list themselves.
Viruses and spam-bots are now designed to go through mail files and address books looking for potential addresses. Sending a single message individually addressed to a large list of people increases the chances that they all will be spammed or sent a virus should any one of them get infected.
Out of respect for your recipients, would you please consider not listing them each individually in your mailings?
If your "mailing list" is personal, you can just use BCC for all the names. (You can send it To yourself.) If it's a more business oriented list, why not make it an official mailing list at your site and use the alias rather than including everyone's name and email address in the headers? You can set up free mailing lists at Google Groups or Yahoo! Groups. To protect your list from abuse, you still may wish to BCC it.
Interestingly, not using BCC when sending email to a large group who don't know each other appears to be against Google's Gmail's program policies. They list as one of the prohibited actions, "to distribute the email addresses of any person without their consent."
Here are some of other sites on the use of BCC: