How to do mass mailing without revealing the email addresses of recepients

I have a blog Blogger Tips and Tricks which is pretty popular with bloggers using the Google Blogger platform and which they found indicated by the comments and the emails I received. For example, this comment left by a reader: "Your text is very well explained and leaves no doubts about the use. I'm finding your site very useful and easy to follow. Thanks for your help!". Further, today, to my suprise and delight, I received an email from a DMOZ (Open Directory Project) editor, saying he found my blog informative and have listed it in the directory, and I didn't even submit my blog to DMOZ! You can read about it here: DMOZ, the most important and most difficult directory to get listed - Blogger Tips and Tricks got listed even without submiting.

Anyway, this blog gets lots of request for help in the comments as well as by a special email meant for blog visitors to contact me. I use gmail for blog readers to contact me, and with gmail, email addresses of people who contacted me via that email address are automatically added to the contact list. I have a long list of email addresses in the contact list, the great majority of which were obtained from emails requesting for help with Blogger. Anyway, I make all links to external sites open in new windows, and there are views that it is back practice as it irritates visitors and may discourage return visits. Anyway, I set up a poll to get the blog visitors views and if you are interested in voting (I hope you would do that) or if you are just interested in viewing the result, visit Real Poll: Should links to external sites open in new windows?. It is also a post to show how a poll can be set up.

I was genuinely interested in the result and was hoping for a wide participation. I though it a good idea to mass mail those in the contact list as the majority had received help from me and I thought a request to participate in the poll is not too much to ask in return for the favour. I realise too late that by doing so, I am exposing the email address of all those in the list. Some complained, and one apparently replied to all, which caused further upset. One demanded I sent out an email to all those receipients apologising for my mistake, asking them not to reply to all, delete the original mail and delete all the email addresses from their contact list. Well, I am the type who are willing to be corrected and to apologise if I make a mistake, but don't want to repeat the same "wrong" by mass mailing and exposing the email addresses again. He taught me to us put the email address via the "Add BCC". I had to copy-paste the email addresses of all those in the list into Notepad and tried to send out the mail that way. Unfortuantely, it returned an error message saying some email addresses in the BCC was not well formed (or something to that effect). I did some testing and found out that it would work if you add a comma to the end of each email address. I did that and successfully sent out the apology without the email address being revealed. So I think this is a good tip for you if you ever want to mass mail people in your contact list, but don't want to expose their email address.