how can I broadcast a changed email address to my contacts list

In the menubar of Addressbook. Address Book > File > Send updates..

Regards,

Captfred

There is one thing to be careful about though when using the "Send Updates" feature in Address book to notify your contacts about address/contact info changes.

Addressbook will automatically include your personal vCard at the end of the email message that goes out to your list. I did not realize this at the time and it royally burned me. My default address card had a lot of extra personal information contained within it that I did not want people to see. There was no indication that the vCard would automatically be included nor any way to disable this feature just before sending the "update" email. As a result, my list received my private information and the only thing I could do was to send a new email to the list manually, minus the vCard attachment, requesting that they please delete the first email in favor of this new one. I'm hoping that most will disregard the vCard, though I fear the damage has been done.

I later discovered that the preferences now include a checkbox for enabling/disabling a "private me card", which allows you to control which content is included in your vCard information. This is handy now, but I wished the default had been to have vCards turned off / not included automatically, since it was a feature I didn't discover until AFTER my updates had been sent!

Running OS 10.7.5