Chandra Announcements currently takes the form of a Google Group. The archive of announcements from 2014 to the present can be viewed as "posts" in that group. Older posts are linked below.
If you would like to subscribe to receive future Chandra Announcements, send any email message to the address:
The page linked above is an archive of all announcements that were emailed from the CXC to the Chandra Announcements list prior to March of 2014.