Do you send out group emails? Did you know that when you put all the email addresses in the To or even CC (carbon copy) fields that you are sharing the email addresses with EVERYONE in the email? This is uncool unless you have permission from everyone to share. If you are emailing a group of friends or family this is OK, but if you are emailing a group bloggers you should use BCC (blind carbon copy). Each person will get the email from you but they will not be see the other email addresses and can only reply to you.
It's very easy to send an email BCC. In Gmail you click the Add Bcc link and add your addresses in that field separated by a comma.
In Thunderbird, you can just pull down from To: to Bcc:
Some people use an email/newsletter service that keeps emails private, so this quick advice is for people that send out group emails by hand.