I’ve been terribly busy lately but I’d like to collaborate a little on this matter.
The use of BCC is a fundamental rule of netiquette, nobody should send any email to several recipients in other way. I cannot understand how I receive lots of emails from computing professionals who should know better on which they are disclosing their entire customer database. Another important rule is deleting the old headers when resending an email. As a general rule we must avoid publishing any email address different as ours.
When writing on public forums, specially on Usenet news, it would be convenient masking our email address making it only human readable as in juanmaria(AT)hotmail(DOT)com or any similar way. Spammers have scavenging programs that filter postings on public forums to get email addresses to add to their databases.
We must never answer a spam message. The removal instructions are usually a means of knowing if an email address is alive. Once you’ve answered, your address becomes more valuable for those spammers.
When using BCC is not necessary to type any address in “To:” it works fine either way.
What I cannot understand is why using BCC helps you fight against viruses. What is true is that if you have only a few contacts in your address book you’re going to spread the virus less than if you have hundreds of addresses. But it won’t prevent your computer from being infected.
“Traditional” viruses, as .exe or .com or other less traditional as MSOffice macros can only be caught by opening an attached file. But, since most people are using Outlook Express that is one of the most virus-friendly email software never written, some new worms are being written to take advantage of the security flaws of this software. Those worms can be spread only by reading a message without opening any attachment and, although usually harmless to your PC, are highly contagious. (Sorry Jackie, I learned about them only a few weeks ago.)
If we’re still using Outlook Express (I’m so used to it that I cannot switch to other) we can prevent catching any virus following those tips -I don’t have an English version of Outlook Express so some of the messages I’m going to write may be a little different-.

- We must deactivate the “Preview panel”. This is one of the most virus-friendly features of this software, it opens emails without our permission. You can find this option under the “View” menu, in the “Design” option you must see a checkbox that you have to unmark. After this operation you’ll have to double click a message before opening it so you can safely delete any suspicious email. Nobody but you must decide which emails are opened and which are not.

- We can read a suspicious message without taking any risk. We can press the mouse right button over this message, click “properties”, click “Details” and click the “View source code” button. We’ll get a raw and pretty messy version of the message but totally harmless.

- From time to time we should visit “Windows update” by selecting the appropriate option under the Internet Explorer “Tools” menu. Once there we can download and install the latest security patches issued by Microsoft.

- Of course, having a good antivirus software weekly or daily updated is the best warranty against virus infection. Opening an attachment before scanning it for viruses is a most risky behavior.

Well, if you're still awake at this point I’d like to recommend you taking some strong barbituric to treat your sleep disorder.